Editing Fan Card Creation Guide

The [[Fan cards|Fan card]] Creation Guide is an extensive collection of tips and guidelines for fan created cards written by user rinkworks; Aquila later wrote an expansion/updated companion piece to it. The guide is well respected and often referenced in the design and critique of fan made cards. 

The rinkworks guide is reproduced here in its entirety, with edits for clarity, formatting, and omitting outdated (first edition) information, with additional content from Aquila and users credited on the edit history of this page.


== Introduction ==
Way, Way TLDR: Playtest your fan cards.

The first rule about creating custom fan cards for Dominion is that you can ignore every single rule about it if you want to. Dominion is a game. Its purpose is fun. If you've got a card idea that sounds fun, do it. Playtest it. If it remains fun after scrutiny, keep playing with it.

Donald X. Vaccarino, the creator of Dominion, on house rules and variants: "I encourage people to play whatever game variants they want, provided they comply with local laws and are agreed upon by all players."

However, this guide might help you create balanced cards without falling into as many pitfalls along the way. If you get past all those, you might still have trouble figuring out how to cost your cards. This guide might help you there, too. Additionally, the later sections of the guide discuss issues related to creating artwork for your cards, printing them, and using them.

Dominion is a very simple, highly flexible game model, and it's very easy to add to. With that flexibility, though, is the potential to make uninteresting ideas. Whilst they may not be flawed, your ideas could get to be disappointing in some way after playing with them for a while. Particularly disappointing if you went through the trouble of getting them printed out.
This guide aims to help make your good ideas into great ones before the final send-off to print, big reveal to your friends, etc.; it goes through the design process, identifying where people can take a bad turn, aiming to help refine your card ideas to be just what you want them to be. Whether a single card or a whole bunch of them, or your own expansion, this is going to help.

This guide may look like a rather serious, studious look into the field of Dominion design, but I'm well aware this isn't the most important thing in life and I'm not pretending to be a second Donald X. I just settled into playing and learning the game, the idea of making custom cards came up some day, and I fell in love with the thought instantly. I like designing, and Dominion is a simple yet diverse game that is amazingly expandable. This guide is the product of about 2½ years casually exploring the field, written through personal interest and seeing how the forum is continually active.

Some quick notes on courtesy: 
*If you're going into fan card creation with the goal of showing Donald X your cards so he can tell you how good they are and that they'll be in the next dominion expansion, don't. With the exception of {{card|Courtyard}}, DXV dislikes card submissions, avoids the Variants & Fan Cards subforum, and gets upset when they're posted in the endless interview thread. Don't be a jerk to the only person who can get Dominion cards printed legally.
*If you're going into fan card creation with the goal of expanding your bgg resume via posting your fan-expansion, don't. That's thin ice, legally speaking. 
*If you're going into fan card creation with the goal of adding all your cards to wiki.dominionstrategy (this site), don't. That's not what the wiki is for.

== Glossary ==
:''You may also find the regular [[Glossary]] useful''.
Flavour and theme are used interchangeably to refer to a card's name and its story, and how the other properties of the card connect to it. Mechanics and functions/functionality refers to everything the card can do. A card's properties are its name, abilities, types and cost.
Direct payload refers to anything that can directly help getting ahead on {{VP}}, so {{cost|}}, +Buys, {{VP}} tokens, gaining Victory cards and sometimes cursing Attacks. Drawing cards, gaining non-Victory cards, other Attacks, and trashing would be indirect payload.

== General Tips ==
*Be open minded. When you get an immediate good feeling for an idea, note it down straight away. Know the rules and makeup of Dominion well (but you don't have to be a top pro player). Refer to the [[#Research|Research]] section for help.
*You will want to break away from your projects occasionally. Don't try to battle through if you're on a time constraint - the end results will not be of the best quality - rather factor them in to your schedule. Keep clear notes so you know what you're doing when you come back.
*To make a design fun to play long term, focus on the mechanics first, then its theme. The more open it is to interactions, whilst having a definite primary function so it can't do everything, the more replayable it will be and hence interesting long term.
*Design briefs for individual cards should specify something relating to one or more of its properties or needed mechanics, and be understandable to another person.
*Each card you make should be on the same power level as the official ones and a fun or interesting play experience.
*Before doing any playtesting, imagine your ideas in the game as you create them. See how one change or addition affects every other aspect of it. Running a few solo tests may help.
*You should be able to sum up what your ideas do in one quick sentence.
*For testing simplicity, get another player to explain what your ideas do.
*Upvotes on the dominion strategy forum show a good first impression, not necessarily a good overall design.

So now let's follow the order of the design process and apply it to Dominion. No matter how you make your ideas, with paper notes or mental ones, casually or organised, you're going through the same process to get to your final outcome. Even if you have ideas down already, it's still beneficial to backstep and look at the basics, in case you struggle to refine or add to your ideas. If an idea you have turns out bad at some point, it isn't necessarily a lost cause; you can step back and tweak things to try and save it.

=== Know Your Canon ===
Be intimately familiar with all of the official Dominion cards and how to make the best use of them. You don't have to be an expert Dominion player, but you should be an expert at knowing what each card does and when and why you'd want to use it. Okay, so you don't technically have to know ALL the cards, but my point is that there are more design principles behind the published cards than you might think at first glance.

For example, do you know why {{card|Sea Hag}} discards the top card of your deck instead of just having you plunk the {{card|Curse}} on top? (Answer: So multiple Sea Hags don't completely destroy your next turn.) Do you know why {{card|Tournament}} gives +1 Action? (Answer: So a player with a Tournament in hand but no Province doesn't have to agonize over the uninteresting decision to risk playing Tournament at the expense of another terminal Action in his hand.) Do you know why {{card|Outpost}} won't let you take more than two turns in a row? (Answer: Otherwise you could build a deck that plays an Outpost every turn, shutting out all other players.)

Knowing why the official cards are the way they are will keep you out of the same traps they avoid.

=== Beyond the Canon ===
The [http://forum.dominionstrategy.com/index.php?board=14.0 Secret Histories] and [http://forum.dominionstrategy.com/index.php?topic=5799.0 Endless Interview] both have extremely valuable insights into what has and hasn't worked with official DXV playtesting. 

The [http://forum.dominionstrategy.com/index.php?board=11.0 Variants and Fan Cards subforum] - especially the [http://forum.dominionstrategy.com/index.php?topic=18987.0 Weekly Design Contest thread] - can be a treasure trove of useful jumping off points and ideas that both work and don't work; a caveat with these is the date they were posted compared to which sets were available as "official" reference at the time - several things that used to be a semi-viable card were suddenly made overpowered in games with {{Project|Capitalism}}, or an official card did them better.

=== Keep It Simple ===
Simplicity is a good thing. You don't want your cards to be any more complicated than they have to be. If you have an idea for a card, try to boil it down as simply as possible without losing the essence of the idea. Note, by the way, that by "simplicity," I'm talking about the concepts you use, not necessarily how complex and careful the the card text has to be to convey those concepts. {{Card|Native Village}} for example, has a wall of text on it, but that's okay since the concept itself is a simple one. Once players learn what it does, they don't have to reread the card text every time just to make sure each use conforms to every nuance.

=== Swing is a Miss ===
Try to recognize cards that will be "swingy" and avoid them, unless adding swinginess to the game is your intention. By "swingy," I mean a card that will tip the balance of the game too much, especially in a random way. In general, you want to reward good strategy, not random luck.

As an example, suppose you had an attack card that allowed you to take the top card of the deck of the player to your left. You might get lucky and turn up a {{card|Colony}}, resulting in a 20-point swing in your favor — more than the margin of victory for many if not most Dominion games. Or you might get very unlucky and turn up a Curse, resulting in a 2-point swing against you. With such a card, strategic play scarcely matters. The winner is whoever gets luckier with that attack.

Swinginess does exist in the official Dominion cards but on a dramatically smaller scale. {{card|Saboteur}} turning a Colony into a {{card|Province}} is only a 4-point swing. {{card|Swindler}} turning a Province into a {{card|Peddler}} is a defensible edge case. {{card|Thief}} and {{card|Bandit}} only work on treasure: a plentiful, non-scoring resource. Also note that many of those swingy cards have been removed as of the [[Second Edition]].

=== Scale Model ===
Make sure your card scales well to multiple players. It's okay if a card plays differently with different numbers of players — many of the official cards do, like {{card|Jester}} and {{card|Pirate Ship}} —but you don't want a card that only works with a certain number and is brokenly weak or brokenly strong otherwise. Note that it is no accident that {{card|Witch}} affects all opponents, while {{card|Tribute}} only affects one. The other way around, and neither Witch nor Tribute would scale properly with different numbers of players.

=== Avoid Scripted Play ===
Try to avoid cards that encourage uninteresting strategies. You probably don't want to disincentivize creative or otherwise interesting play. As a trivial example, let's say you had a [[Duration]] card that prohibited other players from playing action cards while it's in play. This would cause all your opponents' Action cards to be dead cards. How would they defend against this? By not buying action cards and pursuing a money strategy instead. That, in turn, would discourage you from using your new Duration card in the first place, and the game would degenerate into a simple race for money.

You can't anticipate everything, but if you spend a little time to think about the impact your custom cards will have, you can save yourself a lot of playtesting time.

=== Fair isn't Balanced ===
Just because a card is "fair" doesn't make it "balanced." A card is "fair" if all players have equal opportunity to obtain the card and reap the same benefits from playing it. Fairness is good. But just because a card is fair doesn't make it balanced.

Imagine a [[Treasure]]/[[Victory]] card that costs {{Cost|2}}, is worth {{Cost|10}}, and counts 100{{VP}} at the end of the game. It's fair, as all players have equal opportunities to obtain it. But the optimal strategy, dramatically excluding all others, is to buy only those until the pile is gone. And then it doesn't matter what you do, because the loser of that race can't hope to make up the VP deficit with mere Provinces. The card is, while fair, grotesquely unbalanced.

Balance problems with fan cards are unfortunately going to be more subtle than this. Usually it's going to be a judgment call. If {{card|Minion}}, {{card|Saboteur}}, {{card|Wharf}}, and {{card|Goons}} had been fan cards, I'm pretty sure the reaction from experienced Dominion players would be to decry them as unbalanced. They do walk the edge. But the point is that balance isn't an objective yes or no but a judgment call: if they greatly shape the games they're in (as is also the case with {{card|Gardens}}, {{card|Witch}}, {{card|Ambassador}}, {{card|Chapel}} and others), does that influence make the game more or less fun?

At the other extreme, as Donald X. has said, if you have a card that doesn't change the game at all, what's the point?

== Design Cycle ==

=== Situation ===
Good news: unlike with the later stages of the design process, your situation can't be criticised. You're making your cards for somebody, for some reason; you want to make sure that person or group of people likes them and the reason is met. Focusing on this gives direction for later. Are you in a games group who want to expand their Dominion their own way? Do you just love creativity and want to make ideas that work? Will you want to share your ideas with the general public so they could play them? After determining who your audience is, what do they like most about Dominion, their favourite cards and play styles?

Note down your target audience and their likes before anything else, as honestly as you can. You now know right away what kind of ideas will bring the most fun. No point thinking about the meanest Attack card if your games group is mostly softies, unless you're aiming to open their minds. Generally speaking, the wider your audience is or the less you know about them, the more simplicity is favoured, so more people can understand your cards; unless your preferred audience is those who like complexity. Similarly a strategy focus is better for Joe Bloggs, as that's how the official Dominion cards are set; unless your audience is those who want to water the serious strategy side of Dominion down.

Next, note down your primary motive for making cards. It may seem daft, but this will help you stick to the main excitement you have for Dominion and avoid deviating away from it too far when you make new ideas. It may also identify trends in how you will design, and pitfalls you could fall into.

==== Some Motives and their tendencies ====
: '''You want to focus on a specific flavour'''.
::The story and flavour of a game are important to its enjoyability, giving it some sense. If you're making an expansion, it will probably have a central flavour, and there could be card names connected to it that just have to be there. And who is saying that you need to stick to European history? For the general public you might stick to it as they expect it, but otherwise, nobody. The flavour can also help some to remember what a card does. Sometimes you can springboard onto a brilliant mechanic idea by thinking about the flavour first, and when you do, get that idea down on paper quickly. It's by no means wrong to think down this route, especially if your audience is casual players, but bear in mind: ''ultimately, what will make a card fun to play long term is what it does, not its flavour.'' If you play frequently, you'll notice the novelty of flavour fades away if a card plays bad. Let's say you resonate with the thought of medieval {{card|Scout|Scouts}} and like the official card because of this; it is, though, a weak card and drab play experience. You would, at least in time, inevitably choose to use {{card|Patrol}} over {{card|Scout}}, and you'd probably love Patrol if it were named Scout.
::So: the ideal is having both great flavour and mechanics, but it's better to focus on mechanics first if you want to use your cards for a good long time.
::Another risk to prioritising flavour is the mechanics may end up being very specific to it, narrow in functionality and not very fun in too many different games. The rest of the examples here are different mechanics motives.
:'''You want to see more done with a certain mechanic or play theme, perhaps expanding the expansion they're in.'''
::There's a good amount of design space in many of mechanics and expansions. Playing with the expansion a lot you may see how something missing could fit in. You will probably come to a final result you're confident in and will like playing with; however, it may not turn out as different or as exciting a play experience as you hope long term. The design process has already been heavily worked for the set, so you could wind up going over the same thought processes as Donald. Consider the whole expansion carefully, and read its [http://forum.dominionstrategy.com/index.php?board=14.0 Secret History]. You could find that ideas you have can already be achieved by certain interactions in it, or there are good reasons your idea doesn't exist. So really check that your ideas are suitably different and interesting. In the [[#In-Depth Research|research]] section there's some tips on using each official mechanic effectively.
:'''You think up an uncovered mechanic, maybe one seen in another game'''
::To make a card you'll enjoy for a long time that adds a lot to the game, this can be a very effective start. It's why each new Dominion expansion covers a new mechanic; it makes a more interesting thus successful product. Your mechanic might be applied to one single card, or several; perhaps it becomes the centre of your own expansion. It might need new components; be open to this to give yourself more design room, but keep in mind your audience may not like handling and storing too many extra bits. It is possible, though, that a new mechanic could detract from the compelling gameplay of Dominion. Consider the core concepts of the game; deck building, card interactions, strategy, understanding and adapting to game flow, some skill. Will your idea add to or take away from these?
:'''You get a vibe when you mentally combine different card properties together'''
::You'll very likely hit upon something exciting. Get that combination written down pronto in case you forget it. You might find out exactly why you feel it would be effective; if you do, try to write that specific reason down, in case the combination of properties doesn't quite let you achieve your idea and you can open out to using different ones to make it happen. From here, simplicity and sensible theme will be your challenge.
: '''“If only there were a card that did this in that game!”'''
::You will easily get a feel of how the card plays before testing it, and you might get a similar vibe that needs writing down quickly. Here especially you'll need to check the idea isn't flawed (see Research section), as in another kingdom the card will be very different. Also it'll be very easy to make a card be too niche to be interesting for a lot of different games; '''the more open a card is to interactions whilst having a definite function, the more replayable it will be and hence interesting long term'''.  You might put together one super fun kingdom that you can replay and it still be interesting, and that of course is great; but eventually your play group will tire of it and want a change of kingdom. How many different kingdoms can your idea be interesting in, how many different ways are there of using it? Try and elegantly add more functionality if your idea is too narrow.
:'''For the love of creativity'''
::You have the enthusiasm, and the freedom to explore the whole field of Dominion design. You can come across brilliant ideas; but it's easy to get carried away and also make ineffective ones. This guide is written with you in mind, you'd do well to read it and understand good design principles to follow.

==== Practical Advise ====
Finally, think of the practicalities; the time you'll put into your design project and the schedule you'll follow, the money and resources needed to print out physical copies if that's your desire, or how and when to post ideas online. These can prepare you for the process ahead and affect how you design.

Regarding time, here's a reality to know in advance: '''you're going to want occasional breaks from your projects if they're big'''. Your mind will want to stop the learning processes of studying the depths of the game to check your designs are safe, and you'll get creativity blocks. It's natural; don't try to battle through those times, as your ideas will be poor, rather factor them in to your schedule.


=== Design Brief ===
Knowing your audience and why you want to make cards gives you some things to prioritise, a purpose to fulfill. You started off saying you want to make cards; now you can qualify what sort of cards. This qualification becomes your design brief, the bare essentials that your design(s) must be if it's to be considered successful. Try not to add lots to the brief, just the basic essentials; you get to add every desirable trait later in its Specification. Avoid generic terms though; you might want to say 'make exciting cards', but what do you mean by exciting? Or 'different', but how exactly? Or 'that my friend or play group likes', but what's involved there? When you come back from a break, you need to be able to get right back in and keep clear focus. Friends sharing in your project need to understand clearly too.

If you're designing an expansion, it will have an overall brief that most of your cards need to fit. It should include playstyle themes (e.g. [[Seaside|Seaside's]] playstyle themes are the top of the deck and affecting future turns), so that the cards in it have definite interactions with one another. Try to make these themes connected somehow (Seaside's are connected by planning ahead).

If you're making just a batch of cards that aren't necessarily to play together, they probably still have an overall brief of your preferences.

From here, individual cards will each have their own brief. If you have exciting ideas you noted down quickly, these can be made into such briefs. They should each specify something relating to one or more card properties, which may just include abstract concepts of what the card's abilities are to be; so if you later need to tweak the idea, you have its core concept that must stay as is, making things simpler.


=== Research ===
:''For specifics, see the [[#In Depth Research|In Depth Research]] section''
Research may sound boring, but in this case it's nice to do: simply play [https://dominion.games Dominion]! Of course, it'll take lots of games and several expansions for yourself to know enough to make failsafe, quality cards. You can and probably will read up what others have learned by their playing it, like here on this forum or on Discord. The collective opinion of others gets a better general consensus. Sure you might sit down and read everything at once, but probably you'll look up whatever's necessary for each of your card ideas, each brief, as you make them. You might even find inspiration for new ideas too.

With that said, the rest of this section is some generally useful stuff pooled together into one place for convenience (more concrete, specific examples are below in the [[#Common Pitfalls|Common Pitfalls]] section):

==== What makes an official Dominion card interesting? ====
*It isn't always good! Analysing whether or not it's relevant to the best strategies of a game should be interesting every time. If you're using {{card|Rebuild|a card in every game and winning, things will get boring.}}
*It's simple to understand, at least in time. Players aren't thinking about what it'll actually do every time they play it so they're free to think strategy.
*Each one is suitably different from what other cards do. Try to make sure your ideas will be different from any official ones.
*Each is as good as it can be, with no room for improvement. Well, it's more true with newer cards as Donald's got better designing them. Lesson being, time and experience will improve your ideas, but also look for ways to improve as you playtest them. More on this later.
*They're mostly balanced.
*They don't make luck too big a factor in winning. It's unavoidable, but they don't emphasise it. People buy Dominion as a strategy game, but you might be making less strategic, more chance-based cards for a change to this. Make random effects gentle.

==== People's different fun factors ====
*Interactivity between players; there is always a little to be had in every game, such as with emptying piles to push the game towards its end.
*Cards that have several possible functions (each related somehow so they aren't doing everything), enabling creative play.
*Cards needing good play skill to use well feel more rewarding.
*Adding a mild randomness makes for a more casually enjoyable game.
*3-pile endings add an interactive spin, especially in 2-player games.

==== People's bad points about Dominion ====
Consider how your card will interact with these aspects people don't like about Dominion. Will it help alleviate these?
*Not enough player interaction. 
*Shuffle and draw luck can decide some games without strategy being too involved. 
*Cards that take a long time to resolve, either by following the instructions or by causing numerous deep decisions, make players take long turns so they can make the opponents feel disengaged. 
*Long games get boring or too taxing on the brain to be enjoyable. 
*Setup time; (you can't do much about this as a fan card designer unless you want to program your own homebrew dominion client.)
*4+ player games tend to cause too much pressure on 3-pile endings to be enjoyable, which limits possible strategies. (You can't do much about this either, other than not play 4+ player games.)

==== High skill vs Low skill ====
You might want to make challenging cards hard to use well even for experienced players, or easy ones for a more relaxing game. How do you make them?
Compare the [[Empires|Empires expansion]] with the [[Dominion|base set]] or [[Nocturne]], as Donald designed these to be high skill and low skill respectively.
High skill cards look for fine margins: precise times to play/buy/gain, or how often to do so; precise play order of cards during the turn; decks built in exact ways, with each of these rewarding well. Low skill cards make these margins wide, easy to attain or discern, or ignore them.
High skill cards avoid being random as much as possible, whilst low skill cards don't mind or may like some randomness added.

==== What makes a card strong? ====
Every game is different, and every card can be amazing one game, terrible the next. That's how things should be. But for general strength, likelihood of being good in a game, play experience with the card is the real indicator. The [http://forum.dominionstrategy.com/index.php?topic=19276.0 Dominion Cards Lists on the General Discussion forum] give the average consensus of serious players for the official cards, to give an idea for what's strong. Not many people vote and affect the rankings there, so it isn't reliable evidence, but still good. 
* [[List of Cards by Qvist Rankings]]

The [http://forum.dominionstrategy.com/index.php?topic=19871.msg810176#msg810176 ThunderDominion rankings] from Discord give consensus of cards' strength within sets rather than cost brackets.

=== Specification ===
The specification stage is the criteria your project(s) must meet.
After research, you should know the points you need to bear in mind for each brief that you have. Now you can make the specification for each of these briefs, starting with the one for the overall expansion if you're doing one of those. This is a list of the criteria your idea must meet; your brief broken down into individual points, what your research identified with regards avoiding bad or flawed design, your audience's preferences, and expansion themes. Include every other desirable point you can think of, even if not essential, in case they can influence any tweaking later or make one variant of an idea favourite over another. When all the more important criteria are met in your spec, your idea is good to go; you can declare your project complete.

There are 3 points that should be in every specification. Of course, no one is forcing you to add these, but they are fundamentally what makes a great fan card.
# '''Must be balanced''', be on the same level of power as the official cards. You would do well to make this the most important criterion. Playtesting is important to proving this. Expansions: there should also be balance amongst the cards in it, i.e. no card should be left completely ignored if the expansion is played by itself, and no one card should completely overpower the others.
# '''Must give players a positive experience'''. Several different factors are involved here, qualify this further according to your target audience's likes, being precise and avoiding generic terms; if it's the general public, go with the official game's fun factors though don't necessarily expect to excite everybody. Expansions: choose mechanical themes that create fun for your audience and make sure the cards in it cover them well. They should feel compelled to play the expansion by itself.
# '''Must play suitably differently from any official card your audience has'''. (If that's the general public, all of them.) Why make it otherwise?

In notes, the spec can be drawn up into a table, with columns being criteria (it's a good idea to put them in order of importance, so less important ones could get away with being unfulfilled if needs be), reason for criteria, how to test and test results. This will prepare you for playtesting, and identify some things you can test out by yourself to make the experience better for friends if they want to playtest too. (More in the [[#Playtesting|Playtesting]] section.)

Writing down the reason for each criterion can help confirm how suitable and important it is, in case you should see the need to re-evaluate later; this may happen if you identify you have 2 or more points that can't possibly all be met, and you need to work out which to ditch. It will also help you to see how well justified you are in taking designs down certain directions, which can be either a confidence boost or a guide in a better direction, both needed.
You'll fill in the how to test column later, once the spec becomes a design idea.

Here are some suggestions for further criteria:
*Be easy to learn, simple to understand. A complex or wordy card should quickly make sense. (Reason: each game with it is otherwise less relaxing or enjoyable and more of an academic exercise.) *Expansions: interactions between the cards can be as easy or as hard to spot as you like, but the less rules errata you need to make for them the better.
*Be usable in any kingdom. (Reason: because your audience fully randomises each game, and that's how official cards are designed.) Expansions: to be truly defined as an expansion, you should have this in the spec of all the cards in it. You may be making a set of cards to play by themselves though, in which case this point is optional and you call the set a Dominion spin-off.
*Have short enough ability text to allow for a large enough font size to read easily. (Reason: an easier play experience overall, and some audiences need it.)
*Be safe from any possible future card design that doesn't exist officially yet. (Reason: they could exist as fan cards that your audience potentially plays with.)
*For expansions, you could specify the number of cards there are to be in the set, the number at each price point, how many should use a certain mechanic, or definite card flavours that have to be there to reflect the expansion theme.

=== Design Ideas ===
Design ideas are how to translate your specs into effective designs.

At last, time to unleash your creative flair! You've set your restrictions, you've got an idea of where your cards are going, now you can set them off on their design journey. You could still take bad turns despite all of that work beforehand, so go carefully.

Start with the card properties you mentioned in your brief. Then stop. Imagine the card like this in your mind; get the nature of the card, asking these questions:
*What's it like in the deck, in your hand, played, bought?
*How would other players feel?
*What are all the things it does in every situation?
*Do those things feel pleasant and elegant all together or is there a clash?
*Does it feel too similar to an official card?
*What will it combo with? Any broken interactions with anything?
*Compared to official cards, does it need more power or less power? Or what cost seems best?
*Is it fulfilling all of the important points in the spec?
After the first imagining, see if you can add another property; think what will fit well and be interesting. After adding another property, stop again and go over the same imagination process, identifying the differences. Keep doing this until you have all the necessary properties. This imagining is one of the big keys to being a good designer. With time, you'll be able to do it quicker and develop an innate sense for fan card design, creating good ideas from scratch. That said, newer designers can come across fantastic designs first time, so don't think there must by default be an improvement to make if you imagine everything's good!

You may come across several things that could work from the base idea. In such case, write down the different variants and test out which is best.

Translating concepts into Dominion mechanics can be a challenge. Writing the instructions clearly and succinctly is another. Here you'll want to look up official cards that do similar things and learn their wording. If you have a new mechanic, you may have to use a verb not covered by official wording and (hypothetically) explain it in your card's rulebook.

But at what point do you stop adding things? How much functionality do you add? You should be able to sum up everything your card does in one quick sentence (without mentioning any of the unconditional +bonuses when you play it). You can do this with each of the official cards; {{card|Noble Brigand}} and {{card|Pirate Ship}} look wordy, but they're simply 'steal their money if they're rich, give them a little if they're poor' (notice how the Robin Hood flavour helps here) and 'steal their money to become better payload' respectively. This proves them as easy to learn and remember, and it gives them a pleasing elegance. That's probably two big points in your spec covered.

As you keep thinking about your idea, as the direction it's going in becomes clear, you might decide to make this sentence its brief, if it more accurately conveys what you want from it. You can then feel free to change those first card properties if needs be.

Expansions: it can be helpful to brainstorm here. Have the expansion name in the middle, with the playstyle themes branching off it. Off of these write different related concepts; you should be able to identify a concept linking each theme, so put a line from each of them to it. Then note on how to imply each concept with Dominion mechanics, and if any of these are linked to other concepts somehow draw that on. Then, if you have any ideas for cards or your own mechanics, connect these onto the map. Keep thinking of links from one part of the map to the other and you will find coming to briefs for individual cards easier: this map represents the interactions and the very heart of the expansion, so very useful (just don't let your friends see it!). Keep in mind it's good for some cards to not interact well, so you define different strategies.

=== Playtesting ===
This is where you prove the quality of your idea.
A test has been defined as measuring a subject against a standard. Your design ideas are the subject, and the standard is the plethora of official cards that exist and the average game that those cards make. The impact on your target audience and how well it fits into the average game (its balance) is the test. In other words, you're checking the last 2 big points on the spec of each of your cards, balance and dissimilarity, whilst confirming the first 2 from your imaginations, how interesting and easy to learn they are.

This is not going to be an easy section to write, as every possible design is going to need a different test. You're going to have to do some thinking yourself. Here's where the how to test column on the spec of each idea comes in. For balance, think about how you can use it to make a powerful winning deck, noting down what other (kinds of) cards would be needed (don't forget any synergy with itself!). For positive experience, note down how you imagine the card to be interesting, in what situations. For playing differently from official cards, write down all the ones that share similar functions, if there are any. For easy to learn, beyond the one-quick-sentence rule there's only one thing you can do: playtest with your play group. Text size is simple, as explained just below. Any other points you have will either already be met in previous stages or be tested at the same time as the big three. If not, you can probably work out what to write.

=== Preliminary Testing ===
You can probably do this by yourself; You may not need to if you've had friends all the way through your project, and that's of course fine, testing everything together can be fun. But if you're doing the project by yourself, there are some tests you can do first before showing the cards to your friends, to make the experience better for them.

You want to make prototypes of each of your ideas and simulate games to yourself. They're only prototypes - you don't need to go fancy with them! Writing them out on pencil and (card-sized) paper lets you make any needed changes. Then, you can set up a game as normal, adding whatever your design requires, and use any kingdom pile or pile of blanks and put the paper over the pile. You have to remember that any kingdom pile you use like this isn't doing what it normally does, which can be tough at first but you get used to it. An easier but costlier alternative if you sleeve your Dominion cards is slip paper prototypes in all the cards of the substitute piles.

You will also need a counter or somewhere to keep a tally, to count turns.

=== Generic Tests & the order you do them in ===
These are generalized tests; don't do them if you don't care about their result - after all, your design spec is your project.

==== Text size test ====
Open up the [https://shardofhonor.github.io/dominion-card-generator/index.html card generator], and type in your card's instructions in the Description box. How easy is it to read on the generated mock-up? Simple; you don't need to do anything else here.

==== The Feel test ====
You don't need to count the turns for this. Take your idea and put it in a kingdom with cards you know will combo well with it. 

How does it behave? Actually playing with the card can reveal things your imagining it couldn't see, which may make it stronger or weaker than you thought. 

How exciting does it feel when it's in its element? It may not necessarily excite you, but can you imagine it exciting your audience? Can you identify ways it could safely be more fun? Also, how easily are you playing it out? If it's complicated or slow, how can you speed it up or simplify it without deviating from the brief? 

Next, check how exciting it is in a couple of random games: is it nice to analyse at the start of each one? Ignore the novelty of it being your own idea, that's not the excitement you're identifying. If it isn't an interesting process, that suggests your idea is either too open or too narrow in functionality, missing the sweet middle ground, or it's niche but too weak or dull when it's good. 

For expansions. once you have 10 or more individual card ideas for your expansion, put them all together in a game and get the feel of the interactions going on. This will be better if you tested them all individually first. Try to have a fresh mind for it, and play them as best you can; now sure, it's giving you an advantage over your friends, so by all means save this for when you're with them if you wish. But the point is, see if you're thinking along the lines of the playstyle themes of your expansion. You could easily come across some strong combos in the process; note these for the later speed test.

==== The Comparison Test ====
Only do this if your idea is similar to official ones; if it's utterly unique, you can't compare it to anything. You're aiming to check for balance by putting it against the official cards you know are balanced, and how different it is to play. 

Take it and those that share similar functions and put them against each other in similar deck strategies. Simulate a 2-player game where one uses your idea. Unless a card in the game needs the deck to be as normal, you can take the shuffle randomness away from both sides by flipping each deck over, and when you draw a card pick any from the deck. See if you're satisfied with how different the feel of playing each deck is. 

Which one is winning out, and why? If you don't see any reason within the mechanical differences of your idea, play the game through again in case your execution could've been better for either side or if turn order was a factor. If it's only a slight win, see if reintroducing shuffle randomness makes any unexpected distinct difference. If one is definitely winning more, really keep trying to pinpoint any reason why; sometimes it can be a very deep matter.

==== The Speed Test ====
How quickly can your idea make a deck that gets to a win condition? Too fast and it's imbalanced. Take the same combo cards you had for the feel test, take your method of counting turns, and flip the deck over to avoid shuffle randomness if you can. Think which game end method is best for your combo's strategy, and simulate an opponent if player interaction is needed. Run the game with the best possible card drawing, adding 1 to the count after every round of turns is finished. 

If you're going for Provinces, the turn threshold that indicates balance will vary depending on how many different cards are in the combo, not including the base cards. If you have 2 kingdom cards, getting 4 Provinces after turn 12 is safe; if 3, 4 provinces after turn 10. You might justify quicker rates as balanced if the cards in the combo are very niche and weak overall (an example is Beggar with Guildhall), since it will rarely come up and very few different cards could replicate it. If you can find a combo that gets them faster using 4 or more cards, that's fine; it shows the potential your idea has, and the chances of all those cards appearing in the same game is slim. If you start the game with a $5/$2 split of money on the first 2 turns, that has about 11% chance normally; you might justify a stronger combo because of this, or disqualify it if you want to avoid that narrow chance deciding games. 

If, though, your idea aims to get VP in its own way to win, make a kingdom that helps make it strong enough, and run it against a deck gaining just Provinces. Can it win? In how many different kingdoms could it win? You need it to win only some of the time, and you're aiming to figure out how often and get to a satisfactory rate. 

If you need to test out a 3-pile ending, do this with others, as that's the only way to truly simulate it; get the actual mentality of different people rather than trying to imagine them, as you could easily end up biasing their decisions to the outcome you want.

=== Tweaks ===
Your solo testing may reveal some needed improvements. Try to first think about tweaks, the smallest changes you can make, so you don't interfere with the thoughts behind the previous stages of the process too much. Test these out, and if there are still issues think about bigger variants, perhaps at different costs and power levels. All this testing may seem arduous at first, but with time you can add to your design sense as described at imagining your ideas, so you may be able to lessen this part of the process.

=== Using the Variants subforum ===
Here you can call upon the help of other experienced Dominion players and designers at any stage of the design process. Outside perspective can be extremely valuable. What's generally appreciated is that you start your own thread for everything to do with all your ideas, or one separate one for each of your expansions. You'll probably also get more response if you post design ideas up rather than just your situation or brief, even if you feel the ideas are bad (admit it if so); ultimately design work is yours to do, and ready-made ideas are a more interesting read. That's why I've put this section under testing.

People may upvote your ideas. That's great of course, but just be clear on what that means: a lot of upvotes shows your idea gives a good first impression, not necessarily a good overall design. It has the exciting factor, but there could be deep underlying problems that people don't see at first. Conversely, a few upvotes or none at all doesn't necessarily mean your idea is bad, imbalanced or boring; its interest could be subtle and more apparent when actually played with.

You may get feedback replies. Again, this outside perspective can be just what you need, and things can be picked out that you missed. Be grateful and be open to what they say. To improve the quality and relevance of feedback, you might mention your situation, the idea's brief and extra points besides the big four in its spec (they're generally assumed; so is being playable in any kingdom, so if you're making an expansion to be played by itself say so), so people get on your wavelength.
Mocking up your ideas with the stickied card image generator makes for an easier read (link images to your thread using an image hosting site like Imgur), but it's optional.

=== Playtesting with your Group ===
In pure testing terms, the principal advantage here is the outside perspective of your ideas in gameplay, and the reality of different players. Though of course, having fun is the bottom line of board game sessions, and you have to respect that. Set up a game as normal for the group (whatever you do when making an all-official kingdom, don't deliberately select the combo cards like you do with solo tests), making things seem as natural and relaxed as possible. You could either watch them play and observe critically your idea in action or join in and try to treat it like an all-official game, whatever the group's comfortable with. There are testing advantages both ways; the former is like an enhanced feel test, whilst the latter helps you to see the card as if it were official and if it fits in amongst them.

But before anyone jumps in thinking out their strategy, they need to know what the new cards are doing. Here's the test for how simple they are: get them to explain what your ideas do! If they can, your ideas cleanly pass. If you need to chip in with some explanations or rules errata for specific interactions, ask if it makes sense and hope for a unanimous yes, then play through the game and see if anyone asks about those rules again during it. If they don't, your idea may count as a pass, and seeing if they remember when you play it during a later games session will be the indicator. The outcome of this test may or may not identify changes to make depending on how important simplicity is to you, just as long as every game doesn't become an academic exercise.

For the first game or two you're looking for similar things to the solo feel test. Get feedback on how they feel about analysing it for strategy, and any other first impressions they get. As the game goes on and your idea has had a couple of uses, how are they feeling about playing with it? Extra things could be picked out besides your own testing, and more crucially your audience itself is speaking.
Later on, ideally in later games with the idea, you want to check for balance issues:
How quickly are piles emptying? Are games any faster or slower than expected or liked?
How often is the card relevant to a winning strategy? Too often?
Are player interaction effects favouring one person too much? Why?

=== Final Outcome ===
Once all the stages of the process have passed, the spec is as ticked off as it can be and your audience like the card or expansion and can see it just like an official one, it is done, ready to be enjoyed for however many games to come. How are you going to materialise it?

You could keep things as paper prototypes to save on money if your play group agree, or make things more glamorous and print them out nice on paper to sleeve, or even order real cards from a printing company. 
:''See the [[#Mockup|Mock up section]]''

Online, you can present finished ideas on this forum so others can see and play with them. As yet, the only real way to play fan cards virtually is with Tabletop Simulator, which isn't as smooth as ShuffleIT. You have to buy it, then organise meetings with players from around the world since there's no AI opponent option. We're almost certainly not going to see fan card implementation on Dominion Online. Someone could make an app, but to make it shareable with others you couldn't have the official cards on it as that would need Dominion Online's and Donald X's consent.

In any case, if you're using internet images for your card illustrations, carefully find the artist's name and put it at the bottom left of your mock-up, and check the image is free for non-commercial use; if it's from an art-sharing website like DeviantArt or Artstation or from anywhere else where you know the artist is still alive, you should first ask for consent to use his or her work, as this avoids any potential legal issues.

=== Testing Tools ===
Project management tools like [https://hacknplan.com/ HackNPlan] or [https://trello.com/ Trello] are super useful for tracking what needs to be done on a design, organizing ideas, organizing expansions, collaborating with other users, and are free to use and can even incorporate things like image hosting directly into them.

However, you don't need to use them - Donald X. uses a text document and sometimes a spreadsheet and his turn out fine.

== In Depth Research ==

=== Costs ===
This is a big way in which learning the official cards well will help; you can develop a sense for what an appropriate price would be by comparing it with them. Most of the time how strong a card is determines its price, but sometimes there are cases for making a card cost artificially cheap or expensive to help its functions (like {{Card|Chapel}} being cheap to be easily accessible, and {{card|Hunting Grounds}} being {{cost|6}} so it can be remodeled).

Focusing on cost first before the rest of its abilities can make you quite cramped for flexibility, so it's usually better to leave it until last and fit it around everything else. An exception to this is if you're making a card to add more if a certain price point in an expansion. There are often variables you can adjust, like the amount of each +bonus, to better fit a certain cost for balance, so keep open to this.

==== Myths About Card Prices ====
Before I discuss how to price your cards, it's worth saying how NOT to price your cards, so you can undertake that task without any misleading preconceptions.

==== Myth: The Cost Scale Is Linear ====
One of the most important things to remember about card costs is that they are not linear. Since your initial starting deck generates an average of $3.5 every turn, that means the difference between {{cost|2}} and {{cost|3}} -- in terms of how difficult to is to achieve that amount -- is near insignificant. By contrast, {{cost|5}} takes a bit of work to achieve, so the difference between {{cost|4}} and {{cost|5}} is quite a leap.

In general, card costs of {{cost|6}} and up are probably close enough to linear that you can treat them that way. But below that, you should be aware that the jumps between the different costs are not necessarily all equal.

==== Myth: Card costs are proportional to their strength ====
Card cost and strength are usually correlated, especially at {{cost|5}} and up. But since there is so little practical difference between costs {{cost|2}} to {{cost|4}}, costs in that range are more a function of gameplay balance with respect to the opening.

{{card|Treasure Map}}, for example, is not priced at {{cost|4}} because it's "roughly stronger than the {{cost|3}} cards." ({{card|Ambassador}} would take issue with that.) It's priced at {{cost|4}} to prevent players from opening double Treasure Map and potentially cashing them in for four {{card|Gold}}s on Turn 3, which would be ridiculous. Treasure Map is swingy enough as it is, but a {{cost|3}} Treasure Map would reduce Dominion to the strategic equivalent of High Card Draw.

Another example of a power/cost mismatch is {{card|Chapel}}, whose strength would be competitive at {{cost|4}} but was priced at {{cost|2}} for game balance reasons.

[http://forum.dominionstrategy.com/index.php?topic=84.0 These thoughts on pricing, from Donald X., are essential reading for anyone creating fan cards:]
<blockquote>In a game of Dominion, your deck starts out making ~$3.5 a turn. And in a lot of games, it just goes up from there for a long time.</blockquote>

<blockquote>This drastically lowers the difference between costs in the $2 to $4 range (especially between $2 and $3). It doesn't make them identical though. The set of possible opening moves can distinguish those costs. If a card is something you want to use +buys to get extra copies of, that cost is very relevant. If a card is something you especially want in Curse games, you will have less money and the difference will matter. There is perception; people like cards that cost more to look better, and don't want similar cards at the same cost, such that one is "strictly better." And there are special cases. Would Remodel be more powerful at $3?</blockquote>

<blockquote>But these things don't always apply, and as fewer of them apply, the differences between $2 and $4 vanish. Would Village be too strong at $2? You would be able to get a bunch quickly with +buys; that's not game-breaking though. You don't want it turn one, so being able to pick it up with a 2/5 opening isn't so significant, not that you wouldn't do it sometimes. It's worse in Curse games, so that's not relevant. Would Village be too weak at $4? People would still buy it frequently, even though there would be turns when they sadly only had $3. We can glimpse both cases in similar cards, i.e. Native Village and Worker's Village, when what you wanted was Village. However Village at $4 would mean Village-with-a-bonus would have to cost $5, to avoid the "strictly better" issue (and $5 is actually a lot more than $4). So $4 would in fact be a bad cost for Village. And for that matter costing $3 leaves room at $2 for cards that look worse.</blockquote>

<blockquote>For a long time in playtesting, Throne Room cost $3. The extra opening moves weren't a problem and were sometimes cute, i.e. Throne Room / Feast. It was too strong with +buys though - you sometimes amassed too many too quickly. I had to raise it to $4, and that meant getting rid of a Throne-Room-with-a-bonus I had in another set, that had cost $4 but was no good at $5.</blockquote>

<blockquote>Anyway this is how I see it. People talk about the difference between costing $2 and $3 or whatever as if it's a matter of raw power level and well that's not really the way to look at it. It's relevant for $5+ but not for the low end. You want to look at openings and +buys and things instead.</blockquote>

<blockquote>The OP talks about "+1 card +1 action" as worth "less than $2" and well there is no such thing. Without +buys, Village could cost $0 and it would play very similarly.</blockquote>

A more obvious way that card costs can be out of sync with their strength is when there are special circumstances concerning buying them. Grand Market is probably worth $7.5 or so on strength alone, but its "no Copper" clause allows it to be balanced at a cheaper price. Peddler, similarly, is not as strong as an $8 price tag suggests, since its cost fluctuates depending on the circumstances.

==== Myth: Given the above, card strength doesn't matter with respect to cost ====
Well, yes it does. Card strength is not a completely distinct issue from opening gameplay considerations. It's just not, on its own, the only and overriding concern.

However, you do want to be careful about cards that are "strictly superior" or "strictly inferior" to other cards and price them accordingly. {{card|Worker's Village}}, being strictly superior to {{card|Village}} — that is, essentially always at least providing all the benefits that Village provides — kind of has to be priced higher. I say "kind of," because a $3 Worker's Village is more of an aesthetic problem than a gameplay problem. Worker's Village wouldn't really break the game at $3. But if Village and Worker's Village were both on the table at the same time, it would feel wrong, right? And the poor Village pile would go untouched. Pricing Worker's Village higher is better game design, because it keeps both cards useful and, therefore, leaves a larger number of strategic decisions up to the player.

So if you figure out that your custom card is strictly superior or strictly inferior to another card, you should probably price it accordingly, and then make sure the card is still balanced at the resulting price. This may mean that some cards are just too difficult to price well. Suppose your card offers "+3 Cards, +1 Buy." It has to be higher than $4, because the strictly inferior Smithy is priced at $4. But at $5, your new card is strictly weaker than {{card|Margrave}}, which also offers +3 Cards and a Buy.

Note, however, that it doesn't take much to break out of these "strict" constraints. Hunting Party might look funny priced at the same price as Laboratory, but there's at least one case where Hunting Party is inferior: if you have one copy of every card in your deck, playing Hunting Party will just cycle through your deck without letting you draw a second card, whereas you'd get a second card with Laboratory. This is a small case, but it's enough to allow Hunting Party to cost $5 instead of getting stuck with a less appropriate $6 cost.

If you get stuck in a pricing dilemma like this, another option is to use a Potion- or Debt-based cost. Note how Laboratory's and Alchemist's costs are incomparable, because they're priced on orthogonal scales.

==== Myth: Each functional component of a card has a cost; Add those up, and that's what the card should cost ====
It might be tempting to say every +Buy costs $1, and every +Card costs $2, every Curse attack costs $3, and so on. But it doesn't work like that. For example, add +2 Actions to {{card|Woodcutter}}, which costs $3, and you get {{card|Festival}}, which costs $5. You might then think that each +Action should increase a card's cost by $1. But add just a single +Action to {{card|Moat}}, and now you've got something strictly superior to {{card|Laboratory}}. At minimum, it's a $6 card, up from $2. Add +2 Actions to Moat, and you probably have to go to $7, an increase of $5.

==== Myth: Cards shouldn't cost X ====
If you're contemplating a card cost below {{cost|2}}, above {{cost|6}}, or especially above {{cost|7}}, and you don't have a good reason why, there's a very good chance you're doing something wrong. Many fan cards priced at {{cost|1}} or {{cost|7+}} would be better off buffed or nerfed into the {{cost|2}} to {{cost|6}} range. There's a reason why, of the 100+ official Dominion kingdom cards, only seven (excluding the cards with Potion/Debt costs) have costs outside the $2 to $6 range. And one of those, Peddler, usually isn't bought at its base cost anyhow.

Why? On the low end, it's extremely rare to have {{cost|1}} to spend but not {{cost|2}}. On the high end, if you've got {{cost|8}} or more to spend, the correct move is usually to buy a Province (or Platinum/Colony) regardless of what kind of power card might also be available.

That said, there is nothing inherently broken about a card with a weird cost. Let's talk about a {{cost|1}} cost first. Many players feel that there should never have been a $1 card ({{card|Poor House}} due to the dramatic gameplay change it would wreak with {{card|Upgrade}} and {{card|Remake}}. They would no longer be able to trash Coppers outright but instead clog your deck with other weak cards. Personally, I don't see this as a problem. With as many Dominion cards as there are, the introduction of a {{card|1}} card won't change most of them, but it WOULD make a set of games with their own flavor possible. That's the spirit of Dominion -- every game has its own unique set of interactions to puzzle through.

This is essentially the argument Donald X. made before Prosperity came out with its four {{cost|7}} cards. Prior to that, many Dominion players felt that there should never be a {{cost|7}} card, because the {{cost|7}} "hole" was an important and interesting component of the gameplay. But with the addition of {{cost|7}} cards, that "hole" is still usually present, and, when it is not, a whole new set of interactions is available.

On the upper end of the scale, recognize that not every game is a Colony game. A kingdom card costing {{cost|8}} or more might work in a Colony game, but should anything be more expensive than a Province in a Province game? Maybe, but probably not. Even all the official {{cost|7}} cards were made for Colony games, though they work in Province games too.

Again, if you want to make a card with a weird price, by all means go for it. But do be aware that there will be weird ramifications that result. Your job is to make sure those weird ramifications have a positive rather than negative effect on the gameplay.

==== Pricing Your Cards ====
I'm now going to seemingly contradict everything I said in the previous section. I'm going to treat the cost scale as linear. I'm going to break functional units down into cost components. I'm going to do everything you're not supposed to do.

The reason is that although doing all these things is wrong as a proof or justification for a particular cost, they do help you arrive at a good ESTIMATE for what the right cost might be. You do need a starting estimate, after all, if you are to playtest your card.

If you skip the playtesting step, you're better off pricing your cards by instinct, rather than embracing the myths I've gone to such trouble to expose. But if you promise to playtest, embrace them all with abandon, as that will help you come up with a good starting point for your card's cost. Then the playtesting will expose not only any problems with the card itself but the error in your cost estimate.

There's no infallible formula for pricing a card, especially if your card does something unusual. But you can zero in on the correct cost by performing three different exercises and hoping that they all converge on the same cost. These three exercises are:

# Comparing your card to official cards that are similar.
# Calculating your card's cost based on its functional components.
# Playtest your card!

If the results of these three exercises differ, the playtesting step trumps all the others, but you'll probably need to playtest all the more thoroughly to make sure.

==== Step 1: Compare your card to official cards that are similar ====
The first step is to probably to compare your card to the most similar official cards. If it gains {{card|Silver}}, compare it to {{card|Bureaucrat}} and {{card|Explorer}}. If it dispenses curses, compare it to {{card|Witch}}, {{card|Young Witch}}, {{card|Familiar}}, {{card|Sea Hag}}, and {{card|Mountebank}}. And so on.

You can even do this for individual components of behavior. If your card offers +3 Cards in addition to something else, you can still compare the card as a whole to {{card|Smithy}}, {{card|Torturer}}, and {{card|Rabble}}, even if that "something else" is exotic and dissimilar.

If you have a money-earning card, you should compare your card to every other card that earns that same amount. For example, with a card that earns $2, compare it to {{card|Woodcutter}}, {{card|Militia}}, {{card|Navigator}}, {{card|Mountebank}}, {{card|Embargo}}, and -- most importantly -- [[Silver test|Silver]]. If your card earns a variable amount of money, there are still numerous points of reference: {{card|Venture}}, {{card|Bank}}, and {{card|Philosopher's Stone}} amongst Treasure cards; {{card|Harvest}}, and {{card|Secret Chamber}} among Action cards.

Villages benefit most from such a comparison, because there are so many points of reference available to help you. For example, if you have a Village-with-a-bonus card, is that bonus comparable to {{card|Mining Village}}, {{card|Farming Village}}, {{card|Worker's Village}}, and {{card|Walled Village}}? If so, you're probably looking at a $4 cost. But if it's better than that, competitive with {{card|Bazaar}} and {{card|Festival}}, maybe you're looking at $5.

Notice if your card is "strictly superior" or "strictly inferior" to any official card. If so, you'll have to make sure your cost is higher or lower, respectively. Otherwise, you have some wiggle room.

Regardless, the result of this comparison is that you'll probably find yourself zeroing in on a particular reference point. In the best case, you'll decide that your card is roughly equally as powerful as some other card, in which case it's likely it should be priced the same. Again, power level isn't the only consideration, but it's a good starting point.

If you can't find a card that's roughly equal in power, maybe you can find one that is a little more powerful or a little less powerful. In that case, the best starting point might be one less or one more than the card you're comparing it with.

In the {{cost|2}} to {{cost|5}} range, don't forget to consider how the cost changes the card's availability on the opening turns of the game.

==== Step 2: Calculate your card's cost based on its functional components ====
Again, remember that this technically doesn't work, because  
#the cost scale isn't linear and 
#functional components might be stronger or weaker based on what the rest of the card does.

But if you keep all that in mind, you might be able to arrive at a starting guess for your card's cost if you attempt this thought experiment.

It only applies to cards that have functional components that are well-understood. For example, if your card is "Chancellor with +1 Buy instead of the +$2," you can probably zero in on the best cost if you understand what the relative worth of +1 Buy and +$2 is.

So what, then, are the most common functional components worth?

===== +1 Buy =====
An additional Buy is probably usually worth an extra coin, as demonstrated by Village and Worker's Village. Adding +1 Buy onto something is possibly not enough to warrant crossing the {{cost|4}} to {{cost|5}} threshold, but this valuation probably suffices for the lower costs. You should also consider whether the +1 Buy is just an unrelated buff or if it synergizes with what else the card does. For example, the +1 Buy on Worker's Village is just a extra bonus. On {{card|Salvager}}, {{card|Bridge}}, {{card|Goons}}, and {{card|Contraband}}, the +Buy makes the card as a whole work properly. (On {{card|Contraband}}, it allows you to compensate for being blocked from Provinces by picking up two Duchies instead of just one.) If the +Buy synergizes with the rest of the card, you can possibly justify a steeper price bump.

Note, by the way, that a second +Buy is probably not worth the same price increase that the first +Buy is worth. Buys go unused quite frequently; the more +Buys your card offers, the more likely the extras will be unnecessary.

===== +$1 =====
I made a big mistake a while back, thinking that adding an extra +coin onto a card would warrant a {{cost|1}} price increase. This is very wrong. To see how much +{{cost|1}} is worth, just look at the cost difference between Copper and Silver, or between Silver and Gold. Look at Village vs. Bazaar. Look at {{card|Market}} vs. {{card|Grand Market}}, too, taking into account that without the Copper restriction on Grand Market it would be priced at {{cost|7}} or higher. You might cite the small cost difference between {{card|Herbalist}} and {{card|Woodcutter}} as a counter-example, but Herbalist has an extra piece of functionality to boost it up.

Depending on where you are in the cost scale -- and what else the card does -- each additional +{{cost|1}} should probably boost the card's cost by {{cost|2}} or {{cost|3}}.

===== The Second +Action =====
If you have a card that already has +1 Action, and you add a second +Action to it, you're probably safe raising the cost by a flat $1. It does depend on what else the card does. For example, take the second +Action off Village, and you have something much weaker than a {{cost|2}}-cost card. But in general you're probably fine by just flatly valuing the second +Action at {{cost|1}}.

The reason is that adding an extra +Action onto a card that's already a non-terminal doesn't change its ability to be spammed; it only allows you to play an additional terminal action, if you even have one in your hand in the first place. The power of extra actions should not be underestimated, but it's probably unusual for it to be so great that the cost should go up by more than {{cost|1}}.

===== The First +Action =====
The value of adding +1 Action onto a terminal action, however, is a very different consideration. Unfortunately, there is no good formula for it. It depends entirely on what the rest of the card does.

To illustrate this point, let's make up a non-terminal {{card|Woodcutter}}: "+1 Action, +1 Buy, +{{cost|2}}." Since it is strictly superior to Woodcutter, we know its cost should be more than {{cost|3}}. To narrow it down further, we should compare this card to {{card|Festival}} and {{card|Silver}}. The Festival comparison is easy: our non-terminal Woodcutter is the same thing as a Festival without one of its +Actions. That points toward a cost of {{cost|4}}.

We compare with Silver to make sure this is okay. Silver, costing {{cost|3}}, is roughly equivalent to an Action card reading "+1 Action, +{{cost|2}}." Our card is a little better than that, so again we arrive at a cost of {{cost|4}}. Great!

Should we then conclude that turning an existing terminal action into a non-terminal action generally warrants a price increase of {{cost|1}}? Before we answer that, remember the {{card|Moat}}/{{card|Laboratory}} example I mentioned earlier. If we added +1 Action onto a Moat, which costs {{cost|2}}, we'd wind up with a card that is strictly superior to Laboratory, which costs {{cost|5}}. So we'd need to price a non-terminal version of Moat around {{cost|6}} at a minimum. In that case, adding the +1 Action caused a price jump of at least {{cost|4}}!

So how do you know how much +1 Action is "worth"? Basically you have to look at how much more powerful the card would be if you could play multiples. Drawing actions skyrocket in power, because your hand replenishes or grows as you play them. With non-drawing cards, your ability to spam a card is limited by your hand size, but with a strong enough card, that limitation isn't a big deal: You don't need to play very many non-terminal {{card|Mountebank|Mountebanks}} to secure a win for yourself.

But if the other behavior of the card is weak, as is the case with Woodcutter, adding +1 Action probably isn't that big a deal. It all depends.

===== +1 Card =====
As implied earlier, the value of +1 Card can only be assessed if you know if the card is terminal or non-terminal. With at least +1 Action, each additional +Card is ridiculously powerful. +1 Card, +1 Action is probably balanced at {{cost|0}}, but +2 Cards, +1 Action is already priced (quite correctly) at {{cost|5}}. +3 Cards, +1 Action ("Superlab") is a power card of epic proportions that probably shouldn't exist at any cost.

In a terminal card, you can think of the value of each +Card as a function of how much extra treasure it's likely to turn up. At the beginning of the game, each card is worth an average of $0.7. If you consider that +Cards also offers a cycling benefit (usually a good thing if you're buying actions and treasures and a bad thing when you start buying victory cards), the value of +1 Card and +{{cost|1}} are pretty similar. Later on, your average card value usually gets much higher than {{cost|1}}. Later still, the cycling benefit of +Cards becomes a liability. On average, the difference between +Cards and +{{cost}} is probably a wash.

So as a rule of thumb, you can probably think of +1 Card on a terminal action as being worth about what +{{cost|1}} is worth, which is a cost increase of {{cost|2}} or {{cost|3}}. This difference is illustrated by comparing {{card|Moat}} and {{card|Smithy}}.

==== +VP tokens ====
You might be tempted to evaluate how much +1{{VP}} is worth by making some sort of comparison with {{card|Monument}}, but don't do this. The value of +{{VP}} is intimately dependent on how often you can play the card, which, in turn, is a function of the game length (see [[#The Speed Test|The Speed Test]]). And game length can be determined by which specific +{{VP}} cards are in play. Designing cards that use {{VP}} chips is a proposition much too tricky and nuanced to use this component pricing exercise on.

=== Step 3: Playtest your card! ===
Although the previous two exercises can help you come up with a rough guess for what a card's cost should be, there is no substitute for playtesting. Even though you ultimately have to consider lots of different interactions your new card will have with the pre-existing cards, it will probably only take you one or two games to figure out if a card is incorrectly costed. I made up a card a while back that I was certain, based on the previous two exercises, should cost {{cost|4}}. After just a single playtest game, it was blindingly obvious that {{cost|5}} was the correct cost. You don't even have to play a real game -- sometimes just simulating a game will suffice.

Occasionally, cost errors can take upwards of three or four games to figure out, but usually not more than that. It'll just feel wrong. If this happens, try to think about why. That thought process will help you anticipate cost errors sooner when you design the next card.

=== Research: Existing Card Types ===

==== Action ====
The vast majority of cards are Actions; it's the main phase of Dominion, and they have the biggest influence as to what the best strategies are in each game. They need a resource, namely 'Actions', in order to be played, so unless they give +1 Action or Villagers their effects on play will be stronger than a [[#Treasure|Treasure]] or [[#Night|Night]] at the same cost. Since they're played first, they can have a large impact on how the rest of the turn goes.

The presence or absence of +Actions might be the single most defining characteristic of an [[Action]] card. Two versions of the same card, differing only in one having +1 Action and the other not, will likely play wildly different from one another. It's not the differing number of +Cards, for example, that distinguishes Smithy from Laboratory.

There is no firm rule concerning what kinds of Action cards should be terminal and which non-terminal. That decision is largely subjective. However, many fan cards include +1 Action when they might be more interesting without it. Make sure you consider the gameplay ramifications both ways. The right choice will be the one that makes the game's strategy more interesting, not necessarily the one that makes the card more appealing to purchase and use.

Sometimes the lack of +Actions is best. Consider how much less interesting {{card|Courtyard}} would be if it provided +1 Action (assuming its price was adjusted to compensate). The strategic feature of the official version of the card -- being able to save a dead Action card for the next turn -- would be destroyed.

On the other hand, sometimes you need +Actions to make the card work. A terminal version of {{card|Minion}} would be cute but weak; certainly not a card that a whole strategy could be built around.

Adding +[[Villagers]] (or, in {{project|Capitalism}} games, +{{cost|}}) is another way to make a card non-terminal (consider {{card|Patron}}) - then the player can decide whether they want to have the card be the last thing they play or not. However, giving Villagers willy-nilly may destroy the gameplay balance for more kingdoms than you'd like, rewarding stocking up on Attacks and terminal actions instead of building a well-thought-out deck.

Again, though, the distinction isn't always clear, and there isn't always one right answer. The important thing is just to consider the matter and make a thoughtful decision.

==== Treasure ====
They always give direct payload. Make drawing cards with them very hard if you have them draw at all. Keep in mind Actions have already been played, yet the Action resource carries over to the Buy phase. You can't normally play Treasures after you've bought something (exceptions: {{card|Villa}}). Though you may be used to playing all your Treasures down at once, they are technically played one at a time.

There are cases where these are played in your Action phase, and that is when an Action like {{card|Storyteller}} or {{card|Black Market}} instructs you to do so.

===== Potion =====
A Treasure that costs {{cost|4}} and gives {{cost|0P}} needs highly convincing reasons to buy, such as repeated plays producing great effect or accessing a really expensive card. The latter reason can let you make non-Victory cards normally worth $8 or more viable by making Potions part of its cost.

===== Heirlooms =====
One card in the deck from the start interacts with multiple from a kingdom pile; there seem to be very diverse options here. Nothing's saying every Heirloom needs to be a Treasure. It's awkward there being 7 Heirlooms replacing the 7 Coppers already. Either you'll make a kingdom card share an official Heirloom or you'll make a rule for when 8 or more Heirlooms show up in a game. Don't give an Heirloom too much immediate power; the early game is very influential, so they could end up dictating the way to play every game you use them in. 
They can add weak but often useful effects to decks, and the single copy means something that couldn't be done on a kingdom card could be viable. They could get better later on, and they should have a definite interaction with its kingdom pile that doesn't give too much. Think about the Heirloom's average payout over a Copper, and how this will affect the game; will it speed it up or slow it down? When designing the kingdom pile, keep in mind all the mechanics and uses of the Heirloom; it's hard to say which to design first, probably whichever sparked your idea, the cool starting deck mechanic or the kingdom pile needing a singular accompaniment to work.

==== Victory ====
With the possible exceptions of {{card|Overgrown Estate}} and alt-VP like {{card|Gardens}} in an empty deck, these always give {{VP}}. Donald gives some good insight into alt VP cards (those that can make alternate strategies to Provinces, like Gardens or Fairgrounds) [http://forum.dominionstrategy.com/index.php?topic=8559.0 here]. Between these and {{VP}} tokens, {{VP}} cards can be stacked up so points multiply per copy you have, but clog up the deck with weak or useless cards. If you make a playable Victory card that helps the deck, the effect should be weak for the card's cost; always think of it as a source of {{VP}}, and think what would be interesting to gain as a way to get ahead a little. Covering a narrow but useful effect works well as the VP gives a constant reason to buy.

==== Attack ====
One of the major means of player interaction in the game, there's no point making an Attack that kills the fun. Put yourself in the victims' shoes and see if it's interesting to play against; no attack should ever be able to forcibly give them a turn of doing nothing (by itself or when put with other cards), it should be possible to work around it in the absence of Moat variants, and it should make shuffle luck as little of an issue as possible (Knights are about the furthest stretch). Add a self benefit to it, so there's good reason for a softer player who dislikes Attacks to still want to get it; but think of the attack first, then the bonus and cost that best fit. If you add drawing cards, the attack can be launched more frequently as you draw it more often.

===== Trashing Attacks =====
An example of this is "Every other player trashes the top card of his deck." Donald X. frequently mentions this being a bad idea. The problem is that it's too swingy. One person loses a Curse. The next loses a Province. Unless a very swingy, very random game is what you're going for, you need to correct for this variance somehow. And then, even if you do, such cards usually aren't very fun. Players like to build up their decks. They get frustrated at seeing them regress.

The closest an official card comes to using this idea is {{card|Saboteur}}, which corrects for the variance by allowing the player to gain a replacement card whose cost is determined by the cost of the trashed card. Even with this correction for balance, it's one of the least popular cards in the game.

===== Stacking Attacks =====
"Every other player discards a card" is an example of such a card. By itself, it's fine. But if it gets played multiple times -- which, even in a kingdom without a {{card|Village}} or {{card|Throne Room}}, can happen easily in a 4-player game -- then the game can degenerate into a state where players discard most or all of their hands all the time and can't do anything.

Many of the official Dominion cards are great examples of how to circumvent this problem. Notice that Militia doesn't read "discard two cards" but rather "discard down to 3 cards." {{card|Torturer}} does say "discard two cards" but allows a player to take a Curse instead. Sea Hag has you discard the top card of your deck to prevent five Sea Hags from obliterating your next turn.

{{card|Cutpurse}} does hurt in multiples, but its effect is limited to how many {{card|Copper}} you have in your hand. The damage multiple {{card|Bureaucrat}} cards can do is similarly constrained to how many Victory cards you have in your hand, and the "gain a {{card|Silver}}" clause of Bureaucrat cleverly dilutes a Bureaucrat-heavy deck, so that multiple Bureaucrats aren't likely to be played repeatedly throughout a game.

The bottom line is you don't want to have an attack so strong that it can, by itself or stacked, completely ruin the next player's turn. Otherwise you can wind up in a game state where one player is locked out of being able to make any meaningful progress.

===== Targeting & Political Attacks =====
By purposeful design, Dominion doesn't have attacks that target specific players. Many Dominion players appreciate the lack of politics in the game — that is, the inevitable over-the-table negotiations and protests that result whenever a game allows a player to choose a specific opponent to target — and thus may not appreciate a fan card that opens that door. That said, there is not necessarily anything broken about having targeted attacks in Dominion, so if that's what you want to do, go for it.

[http://forum.dominionstrategy.com/index.php?topic=80.0 Donald X on the subject]:
<blockquote>Dominion always had everyone-but-you-style attacks, and the reason it did was because that's what I do in all my multiplayer games that have attacks (that don't have some more game-specific solution). It was automatic. It did not involve any special calculations or testing for Dominion specifically. And then it worked because of course it works, it had already worked in all those other games.</blockquote>

<blockquote>This comes naturally from making games at all. You make a game. It allows for directed attacks. Who do they attack? Man, you designed it. You must be the one who knows what's going on. They attack you. Of course it also comes from evenings spent whining about who gets the robber, man, Tom's winning, put it on that ore why don't you, wtf, don't trade with Tom, are you nuts, he's winning I tell you, look he's just about to get the longest road.</blockquote>

<blockquote>I don't see any reason you couldn't make a game like Dominion with directed attacks. Some people like spending the evening whining about who not to trade with - it takes all kinds - and there's nothing about "your game state is stored in a deck of cards" that defeats that. I personally don't like those games and so Dominion isn't one of them. But if political games are possible at all then you can also make a political deckbuilding game.</blockquote>

<blockquote>I don't agree with some of the other stuff you said either, but it's not like I want to talk about what exactly is possible on a Dominion card. And what, I'd just as soon have people making up directed attacks for their homemade cards; since I won't be doing those, it stops us from overlapping.</blockquote>

===== Attacks that offer no benefit =====
Like almost everything in this list, this is not a firm rule. But before you create an attack card that ONLY harms other players, consider that of all the official cards, there are only two Attack cards that don't also provide some form of benefit to the player. These are Sea Hag, which is so strong for its cost that any additional benefit would overpower it; and Saboteur, which would be even more unpleasant than it already is if there were any additional incentive to use it. Even attacks as brutal as {{card|Mountebank}}, Witch, Ambassador, and {{card|Ghost Ship}} provide additional benefit to the player. Besides that benefit being necessary to achieve forward movement in the game, they also ensure that, if the attack portion is blocked by Moat, the attacking player hasn't utterly wasted his action.

All I'm getting at is that if you create an Attack card with no benefit, make sure the decision not to include a benefit was a conscious and considered choice and not just something you overlooked.

==== Reaction ====
Reactions can be revealed an infinite number of times when their needed event occurs, even after a new copy of the card enters your hand during the reaction (like with Caravan Guard). You need to either make how many times you reveal it not matter, or move it from your hand so you can't reuse it. If the reaction can't always trigger in every game, add something on that makes the card always useful. Making an on-play effect non-terminal (not be an Action without +Actions) lets several copies be added to the deck comfortably so the reaction will more likely and/or more often trigger; cantrip (Action with +1 Card +1 Action) even more so.

===== "No U" =====
Consider a reaction that harms the attacker, in particular reflecting the attack.
This kind of idea comes up a lot. Sometimes the reaction is that the attack is reflected back on the attacker; at other times, some other form of harm befalls the attacker. Also variable is whether or not the attack still goes through to the reactor or not.

The basic problem with these kinds of reactions is that they make people afraid to play attack cards in the first place. And if they don't want to play attack cards, they don't buy attack cards. And if they don't buy attack cards, you won't have any need for your reaction card, either. The end result is that both the attacks and the reactions are left on the table.

There are more nuanced problems, too. [http://forum.dominionstrategy.com/index.php?topic=71.0 Here's Donald X. on the subject]:
<blockquote>
:As I usually tell people who want to show me cards, the obvious ideas are obvious to me too, and I had a big head start. For example Richard Garfield suggested 3 cards while he was playtesting Seaside. One was already in a set and has survived; one was already in a set but currently isn't in one although I have an idea for fixing it up. The third card was the reaction that reflects the attack, which I had had suggested so many times that I had already written up an essay on why it doesn't work.
:
:The problem with defenses that attack is that, in 4-player games, there's a 1-to-3 ratio that goes the wrong way relative to the buying decision.
:
:Let's consider 3 cards:
:
:*Point Eater. An attack that makes each other player lose 1 point. There's no Curse card involved; we'll track these points on a scoring track. I'm doing this to keep the analysis simple.
:*Revenge. When another player plays an attack card, reveal this to make them lose 1 point. It doesn't stop the attack. It only works for you once per attack, one way or another.
:*{{card|Moat}}. As-is.
:
:I am just considering 4-player games here, which is where the problem is at its worst.
:
:I play Point Eater. Each other player is down a point. Or, from my perspective, I'm up a point.
:
:You Moat my Point Eater. For you, that's worth a point - you were going to lose a point, but now you don't. For me, that's -1/3 points. I make two out of three opponents lose a point, which is roughly 2/3 of a point of a benefit. It's rough because, who knows, maybe two of the players suck and I only care about the other one; if that one Moats I break even and if they don't I'm up a point. But in general, it's not like that; I am more or less still up 2/3 of a point when just one player Moats. So again: The person who decided to buy Moat makes a point here - they would have been down a point but are not - and the person who decided to buy Point Eater is still up 2/3 of a point after the Moat. Both cards still reward their players for buying them.
:
:You Revenge my Point Eater. For you, that's worth 1/3 of a point - one out of your three opponents lost a point. For me, the entire benefit of my attack is gone - I break even rather than being up a point. The person who decided to buy Revenge just got 1/3 of a point of benefit; the person who bought Point Eater got nothing. Revenge is a weak investment and Point Eater is horrible. Of course if this means no-one buys Point Eaters then Revenge is useless.
:
:See, it's this 1-to-3 ratio. In the wrong direction.
:
:We could make Revenge three times as powerful - the attacker loses 3 points. Then playing Revenge is worth a point, like playing Moat. Being on the receiving end means losing 2 points net. Attacking is really unattractive in this situation, while defending is just as good as it is with Moat. It's even worse if, as in this example, Revenge is cumulative. Everyone else Revenges and you end up down 8 points. If everyone had Moated, you would have broken even.
:
:Or, we could make Revenge one third as powerful - the attacker loses 1/3 of a point. Then being on the receiving end is just like having your attack Moated - you are back to getting 2/3 of a point for your attack. Playing Revenge is pointless though - you are only up 1/9 of a point. You could make the rest of the card good enough that this was playable, but you would completely ignore the defensive part when deciding whether or not to buy this.
:
:So that's the deal. You can't fix the problem by tweaking the cost of Revenge; you still have the bad ratio. The one thing you can do is change the ratio; for example, Revenge could make every opponent lose a point whenever any opponent attacked. Then it's an attack that your opponents have to enable. Which is not necessarily out of the question, but isn't super sexy.</blockquote>

===== Non-terminal Reactions =====
If you create a non-terminal reaction, it's important to think through the ramifications.  In particular, consider drawing non-terminal reactions very carefully.  The issue is that making reactions non-terminal allows a player to stock up on them and thus pretty much always have one in hand when needed. Imagine adding a Moat-like reaction to {{card|Laboratory}}. You could buy them all up without harm to your deck, render attacks useless on virtually every turn, and still have a strong deck in its own right.

This problem is not insurmountable. The Reaction effect doesn't have to be an "attacks stop dead" effect like Moat has, and/or the Action component doesn't have to be as strong as Laboratory. But if you contemplate a non-terminal Reaction card -- again, especially drawing non-terminals, which do little or no harm to buy en masse -- consider the ramifications to the gameplay if one or more players decide to spam them.

===== Revealing Multiple Times & Ways to Defuse it =====
A subtle but significant rule about Reaction cards is that they can be revealed an unlimited number of times in response to any single event. Many fan Reaction cards aren't designed with this rule in mind. Consider this Reaction card: "When another player plays an attack card, you may reveal this from your hand. If you do, +1 Card."

With such a card, the moment someone plays a single Witch, I can reveal it as many times as I need to to draw my entire deck and discard pile into my hand. The official Reaction cards don't have this problem because they either do not stack (Moat and {{card|Secret Chamber}}, for example, don't do anything the second time that they can't do the first time) or cannot be reused ({{card|Horse Traders}} gets set aside when revealed).

If you have a Reaction effect that could stack if the card is revealed repeatedly, you can solve this problem either by using the Horse Traders mechanic of having the card set aside and returned to your hand later, or you can require that the card is discarded when revealed.

I'm sure these aren't the only viable solutions, but avoid special-case card text like, "You may only reveal this once per attack." The reason is that then it's hard for other players to account for whether you're revealing the same Reaction card multiple times or different copies of it in succession. This is especially true when you also have Secret Chamber, which could potentially rotate different copies of your other Reaction cards in and out of your hand

===== Reactions to things Other Than Attacks =====
Let me be clear: This is not a bad idea. It's been done a couple times with {{card|Market Square}}, {{card|Patron}}, {{card|Hovel}}, {{card|Faithful Hound}}, and {{card|Trader}}. 
There is probably a lot of design space still unexplored for Reactions that react to things other than attacks. The Dominion rules specifically allow for Reaction cards to be able to potentially react to any number of different kinds of events. But a word of caution: If you create a card that reacts to an event that no official Reaction card reacts to, think that through. A bad decision here could severely bog down the game.

For example, imagine the following card: "When another player plays a Treasure card, you may reveal and discard this card from your hand. If you do, the other player trashes the Treasure card immediately."

Here's the problem: Do you really want all players to have to wait, every single time they play a Treasure card, to see if anybody is going to play this Reaction to it? Without such a card, players will often lay their Treasure cards down all at once, which keeps the game moving quickly. But with such a Reaction card in play, it's strategically disadvantageous to do this, as then the Reactor will be able to make a more informed decision about which Treasure card he'd like to trash with it.

To date, the existing Reaction cards only react to events that would require that player to do something anyway. When someone plays {{card|Militia}}, there is already a natural pause in the game to wait for the other players to discard down to 3 cards in hand. The natural pause allows for the timely revealing of a Reaction card, like Moat, and not slow the game down any further. Similarly, {{card|Watchtower}} activates when the player holding a Watchtower in hand gains a card -- another moment in the game when the Reactor would be expected to act anyhow.

I'm not suggesting that Reaction cards should ONLY react to events that cause the Reactor to act. But they should probably only react to what are already natural breaks in the game.

==== Duration ====
The card stays in play for however many turns as long as it's tracking something, be that effects for your following turns and/or during each other player's turns. Remember, start of turn effects are effectively the same as playing a normal Action with +1 Card +1 Action then the effect, so just +1 Card like Caravan is actually the same as playing Laboratory; typically the later effects are stronger than the immediate, and the immediate needs to be weak to balance it. The total amount given across the turns is a lot for the card's cost, but in balance staying out of deck for some turns means multiple copies are needed to keep an effect constantly in play, and they can miss shuffles by staying in play at Clean-up. This type is a diverse and useful way to implement a lot of different mechanics, so be open to using it, just as all the newest expansions from Adventures on have done. Between Durations and Projects: Durations can be multiplied with copies in the deck (with repeated buys) or Thrones, or effects that can't be multiplied call for a bit more work to put out; Projects work right away without deck cycle delay and are continuous.

===== Indefinite Durations =====
There is nothing inherently wrong with this idea, but a minor point: Usually this kind of idea is proposed with a new card type of "Permanent" or something. If the card otherwise behaves like a Duration card, then just call it a Duration card instead of inventing a new type. According to the Seaside rules, Duration cards stay out until the last turn in which they have an effect. Although the specific Duration cards in Seaside all get discarded after the following turn (except for a failed {{card|Tactician}}, which gets cleaned up immediately), the Duration type itself allows for a card to remain out for any arbitrary number of turns.

As of Renaissance, there are two cards that do this - {{card|Hireling}} and {{card|Champion}}. Both involve opportunity cost to obtain - Hireling is expensive and also terminal, and Champion requires climbing a [[Traveller]] ladder to get. 

[[Project|Projects]] and events like {{event|Pathfinding}} can also be thought of as this, with an opportunity cost of a Buy + some sum of money; these alternatives don't stack though - having six {{card|Hireling|Hirelings}} in play is much stronger than having a Project that lets you draw six cards at the end of your turn.

==== Night ====
The Action and Buy phases have passed so you can't give +Cards, +Actions, +Buys or +{{Cost|}} without adding something to make them always useful. The Night type is primarily good for when cards in play, cards not played, cards gained or other events during the turn are important. Unless the events of the whole Buy phase are distinctly involved in their mechanics, pure Nights shouldn't really be direct payload cards, since they'd probably be better as Treasures. They could be gained to the hand, as buying them lets them be used straight away, and Duration effects are easy to put on too, widening the somewhat narrow design space.

==== Ruins & Looters ====
Ruins should be weak and {{cost|0}} cost like the official ones are, so there's as little effect from randomness as possible, just enough to be interesting. You should ask, though, if making more Ruins would actually be worth the cost, because how much could they add to the game for all those cards and your money? The official ones do everything they need to do (unless you don't have Dark Ages, of course). Looters can be strong with Ruins for self benefit, or give them out with Attacks when Curses would be too harsh or when you specifically want $0 cost cards, weak Actions, the Ruins type or several different cards in the opponents’ decks.

==== Command ====
Command is new type that has several rules innately attached to it. If a Command plays a Duration, it stays out for as long as it does. Cards played are left in their location (which could be anywhere there are cards), so any effect that needs them to move, like Reserve cards and those that trash themselves to produce an effect, won't work (every self trash needs to say 'if you do' trash it). Commands from the Supply are good for when diversity and flexibility are important to your idea's interest, the ability to become whatever kingdom card is available when you need it, or to first be an available trasher then something else when trashing is done. 
Commands from places where you don't know the cards that are there make for randomness, or player interactivity if targeting an opponent's hand or deck; bear in mind that this interactivity may not be pleasant as a player's work goes to help someone else.
Commands should generally not be able to play Command cards, to avoid infinite loops and recursion.

==== Reserve & Tavern Mat ====
The Tavern mat is simply a space for cards to be set aside on; the effect this has is different for each card. If the card removes itself from the Tavern mat at some time, it has the Reserve type (although Distant Lands doesn't follow this), and if it's moved into play, it is 'called'. Their being set aside from the deck can be used to balance a powerful on-play effect, if you add some form of payment to get them back (see {{card|Wine Merchant}}). You can be very flexible with what triggers a call, and you could cover very narrow events that would be unrealistic on a Reaction; they don't need to be in hand at the time. Copies of them can be stored up so a call effect could happen multiple times at once. You may think of a toggle effect where being on the mat turns an effect on and removing it turns it off, but think about how easy it will be to remember with the card not being in play; Duration might be an easier format here. Non-Reserve cards can put other non-Reserve cards on the Tavern mat, to both remove them from the deck and be used by the card itself somehow; keep {{card|Miser}} in mind here.

==== [[Shelter|Shelters]] ====
Don't give them too much immediate power; the early game is very influential, so they could end up dictating the way to play every game they're used in. Be very careful around extra money, as the significant boost in strength from {{cost|4}}-cost to {{cost|5}}-cost cards is partly down to the odds of getting a hand of 5 {{card|copper|Coppers}} in the opening over 4 and {{card|Estate}}. They can add weak but often useful effects to decks, could get better late game, have interesting interactions between them, but should still be reasonable to trash.

==== Split Piles ====
You get to add more different kingdom cards to games, create competitiveness by players getting the most copies of each card, and make the lower cards be affected by the timing of their availability. The fewer copies of each card in the pile can be useful too, if there's an effect where too many copies is imbalanced. 
The cards on top need to empty easily so the lower will appear, i.e easy to gain into decks or self-depleting (see {{card|Patrician}}/{{card|Emporium}} and {{card|Gladiator}}/{{card|Fortune}}, respectively); or returning them to the pile can also be effective to balance a powerful lower card (see {{card|Encampment}}/{{card|Plunder}}). The lower cards should synergise with the top ones whilst not making a complete strategy.

==== Non-Supply Piles ====
These are generally paired with one or more Supply piles (consider the [[Prize|Prize pile]] and {{card|Tournament}}; {{card|Madman}} and {{card|Hermit}}; or {{card|Spoils}} and {{card|Marauder}}/{{card|Bandit Camp}}/{{card|Pillage}}). These can be used to upgrade or give a temporary boost to a player's deck, or can contain powerful cards that are difficult to get. These avoid all Supply pile altering effects (like the +bonus tokens from Adventures) so abilities are fixed and unchangeable, which opens up new possibilities; You can achieve different play ‘modes’ of a kingdom card by exchanging it with the non-Supply card; Different cards could gain the same non-Supply card; you can have two cards heavily depend on each other.

===== Travellers =====
Over non-supply pile upgrades, Travellers are probably defined as a card that can upgrade more than once, one stage per turn. Use these to implement a super powerful effect, a whole deck strategy, on the last stage of the line, so it's balanced and interesting by the time taken to get it. You'd think of it first, then the rest of the line. It'll need to be reliable and affected very little by shuffle randomness once played, to ensure the work and wait pay off. The upgrades up to it should complement it, or work against it if it's that powerful. Consider how they affect deck cycling speed too, as that will affect the speed of upgrading. They should escalate in power, can use the advantage of being non-Supply piles, and give varied but related effects so in the right kind of deck you could collect several of different stages. Don't make them do everything though, there are 9 other kingdom piles in the game which need interacting with.

==== Curses ====
Only use this type if your idea replaces the original Curses. If you attach it to kingdom cards and give them negative VP to try and offset something powerful, you can trash them later so there's no disadvantage, so it'll almost always be right to get them. You might give each other player some VP tokens instead though, to simulate a permanent mark against your score.

=== Research: Existing Landscape Types ===
For effects outside the deck that affect the player's turn, deck or the whole game. Beware accidentally making an avenue to a [[#Golden Deck|golden deck]] when designing these, since they are generally not an inherently limited resource like a kingdom card is.

==== Events ====
These can be bought any number of times unless otherwise specified. Use them to add extra global mechanics to games, or goals to reach, without detracting from kingdom card functions so as to retain the deckbuilding aspect of the game. 'When you gain this' effects on kingdom cards are a similar feature; they are limited to the number of copies in the Supply (unless there are trash gainers) and relate to the other mechanics on the card. These might influence your designs.

==== Landmarks ====
Passive effects that to-date have all involved {{VP}}, to affect how the game can be won. They can really add to Dominion's replayability, and really transform the best avenue to take on an otherwise straightforward kingdom. Avoid implying a much longer game with them though.

==== [[Project|Projects]] ====
Not hard to comprehend, you buy them once to activate a continuous effect that changes your gameplay ({{event|Inheritance}} is essentially a Project). These are similar to an [[#Indefinite Durations|indefinite duration]] card, only their effects don't stack.

The main strategic concept is when to buy them (and if asap how quickly the game can let you get there), so cost is important to get right, though there is design space for narrow use case projects, where your main concern isn't ''when'' to get them, but instead ''if'' you should get them. 

==== Boons & Hexes ====
These add some chance element to a game, good for a more casual audience. {{card|Druid|They can be set aside from their pile}} so that a card has some random but fixed abilities for a game, to favour more strategic audiences (although in doing this with Hexes, you will want to consider that card's terminality very, very carefully, since {{hex|Locusts}} and {{hex|Delusion}} are extremely powerful). In any case, a card using them should also have a constant effect so it has a definite purpose. You could probably make your own Boons and Hexes too, keeping the average power level of the official ones in mind - after all, there [http://forum.dominionstrategy.com/index.php?topic=17955.0 were outtakes of each]. The random factor is just enough to be interesting; if they were too much stronger, wins could come entirely down to chance too often, not nice for a predominantly strategy game.
* Noteable outtakes: a +1{{VP}} boon

==== States ====
These are really useful. If you have a mechanic idea that you can't implement cleanly another way, here's a blank card you can write things on to make it work. 1 copy of it (per player if needs be) should be all an effect needs, though you can use both sides (see {{state|Miserable}}/{{state|Twice Miserable}}). Particularly good for unique Attacks (the -1 Card and -$1 tokens are essentially States), although you can change the state of all kinds of things.

==== [[Artifact|Artifacts]] ====
Artifacts are Projects that only one player has at a time ({{state|Lost in the Woods}} is essentially an Artifact), creating player interactivity. They can either be easy to take for competitiveness or hard to take for a way to get ahead.

=== Research: Other Existing Components ===
This section will discuss pitfalls when cards interact with non-card 

==== The Discard Pile ====
You don't want to make cards that care about the order of the Discard pile. An example of this would be, "Look at the top five cards of your Discard pile. Put two of them in your hand."

Usually opening up Dominion's strategy space is a good thing; once in a while, not so much. It's no accident that no official Dominion card cares about the order that cards appear in the discard pile. The moment you introduce one that does, suddenly every player who buys it will have to think very carefully about how they perform every single clean-up phase, just in case they happen to draw that card in the next hand. This will dramatically slow down the game, and most of the time it'll still be wasted effort.

==== The Trash ====
When cards are trashed, they're trashed for a reason. A fan card that does something like "Gain a card from the trash pile" is going to be useless most of the time, because even if there are trashers in the kingdom (and there may well not be), who want a {{card|Copper}}, {{card|Estate}}, or {{card|Curse}}?

If there are trash-for-benefit cards in the kingdom (like {{card|Salvager}}, {{card|Apprentice}}, {{card|Bishop}}, and the {{card|Remodel}} family), then you might find something good in there, but this will only be a small minority of boards. And within that minority, there's a good chance the card will be brokenly powerful, and/or players will be dissuaded from using the trash-for-benefit cards on good cards in the first place.

{{card|Rogue}}, {{card|Lurker}}, and {{card|Graverobber}} retrieve cards from the trash, but they also put useful cards there to be retrieved at a later time.  The balance is extremely delicate; any card that retrieves cards from the trash should be carefully tested.

==== Mats ====
Mats either track cards set aside for an indefinite amount of time, or hold gained tokens and define what they do. At present, no official mat has required you to keep the cards put there in order but that's not a requirement if you have your own idea.

==== Debt ====
Debt is great for making expensive cards, you can't really make a non-Victory card cost more than {{cost|8}} but in debt it's sensible as you split the cost across several turns; but because of this {{debt|8}}  feels equivalent to about {{cost|6}}-{{cost|7}}. Don't make such an expensive card be really good early game (consider {{card|Royal Blacksmith}} because it's accessible then: you might involve this easy accessibility in a card's mechanics though, to make an on-buy effect available whenever useful or make getting copies from a kingdom pile more competitive. You can also use debt cost to avoid being affected by abilities referring to $ costs like {{card|Engineer}}. And remember you can't buy anything if you have debt, it needs paying off immediately.

==== Coin Tokens ====
These are generic. Use them on a card or mat that will define what they do.

==== Coffers ====
An accumulation of +{{cost|1}}s to call during any future Buy phase. +1 Coffers is a bit more valuable than +{{cost|1}} for the extra flexibility, and it's not limited to being useful only at the Action and Buy phase but can be gained at any time. It's bad to make them too easy to collect and hoard as that detracts from the function of the deck.
You can normally only spend these in your Buy phase, which detracts from their usefulness with {{card|Storyteller}} and {{card|Black Market}} - consider using this to cause interesting dilemmas with similar cards you design.

==== Villagers ====
An accumulation of +1 Actions on demand. Villages make for consistent Actions per turn when the deck is lean and can play right through each turn. Villagers make things much more reliable by evading shuffle randomness; this will be temporary unless you keep a constant supply. They make playing Action combos in the right order easier. They can be gained at any time unlike +Actions; use this and their being stored up to make different ways to getting Actions than playing Villages, and if used to make an Action non-terminal make the storing count for something or justify it as a card you could open with.

==== VP Tokens ====
These make alternative ways to win the game, and they don't harm the deck with weak or useless Victory cards. You need to avoid neverending games where players can keep playing turns just getting {{VP}} tokens and nothing else. Every way to gain {{VP}} tokens must bring the game closer to an end, which means gaining cards to empty piles; gain them directly, trash them or your own cards so you need to regain things to trash, or you can give direct payload to imply gaining things. Avoid pairing with getting debt as this will have the opposite effect. Another alternative is make the VP gain a one-shot effect (you could use debt then).

Designing cards that award victory tokens is a trickier challenge than it seems.  The reason is that you have to be careful not to allow a game to devolve into a game state where the optimum strategy for all players is to forego buying victory cards in favor of playing and replaying their victory-token-earning cards.  Then the game never ends.

Of the three official cards that award victory tokens in [[Prosperity]], two of them are tied to finite resources.  {{Card|Goons}} only awards victory tokens when you buy a card, which ensures that sooner or later the game will eventually end normally.  {{card|Bishop}} awards tokens by trashing cards, which indirectly ensures the same thing -- if you don't buy cards, you won't have cards to trash.

{{card|Monument}} is the exception.  In theory, if all players wind up with hands consisting of King's Court-King's Court-Monument-Monument-Monument, you could indeed wind up in an unending game state.  But this doesn't really happen in practice, probably because of two things:  one, Monument being a terminal makes it difficult to spam; two, it offers $, which encourages the purchase of cards.

The lesson these official cards teach us is that if you have a fan card that awards victory tokens, make sure the game can't wind up in an unending game state.  If you can't prove this to yourself with theory (as is the case with Goons), then you'll need even more playtesting than usual to make sure.

[[Empires]] expanded on this a little bit - {{card|Chariot Race}} is a cantrip that can be a peddler+{{VP}} but only if you get lucky; Groundskeeper is a cantrip that can double up on the Goons effect, but only when buying Victory cards; and the [[Gathering]] cards all have their own wind-down (i'm skipping {{card|Crumbling Castle}} because it's on trash/on gain and while I guess you could all collectively gain it then Ambassador it back to the pile, it seems unlikely that'd ever happen, requiring a good deal of cooperation in an otherwise competitive game); likewise, the landmarks that give {{VP}} tokens are all either finite supply or involve trashing/gaining, and so wind-down the game anyways.

==== Vanilla Adventure Tokens ====
That is, the +1 Card/Action/Buy/{{cost|}} tokens - the Buy token is far cheaper to put down than the other 3 overall, but their strength depends a lot on the cards in the game and the player's freedom of choice where the tokens go. Having to spend {{cost|6}} or {{cost|8}} whilst adding no card to the deck, or getting {{card|Teacher}}, should reveal to you the power you're handling.

==== Journey Token ====
A way to have a card switch between two modes each play. The number of copies you have and/or timing become factors for playing the card well. Always force flipping the token, otherwise it's a “choose one” card.

==== Penalty Adventure Tokens ====
That is, the -1 Card and -{{cost|1}} tokens, these are essentially States, and can only be taken once, meaning attacks that use them ({{card|Relic}}, {{card|Bridge Troll}}) don't stack the penalty. These work equally well as self-setback tools for ones' self as attacks on ones' opponents.

The difference between the -{{cost|1}} token and {{debt}} are that the -{{cost|1}} token isn't stackable, it can be paid off in the Action phase with +{{cost}}, and you can still buy {{cost|0}} cards if you have your -{{cost|1}} token and no money.

==== -2 Cost Token ====
Strong when you can take a card below $5 cost with it. Wildly strong if you let it go on Victory piles.

==== Trashing Token ====
All you can really do is apply it with a different method than {{event|Plan|paying $3 and a buy}}.

==== Estate Token ====
Hard to reuse, you can't really add further abilities to cards that do something, and Estates are at a good price and you start with some.

==== Embargo Tokens ====
These have a defined use on supply piles, but not when given to players; You can make other cards/card-shaped things distribute them. These are an underutilized pile-denial method - other methods make work better, however.

=== Research: Existing Mechanics ===

==== Types ====
If you focus on a certain type combo for designs, you could get a narrow, inflexible space to work in, which can limit your card's potential. You might do so to achieve certain necessary interactions amongst your card ideas, particularly within an expansion, but otherwise just add the relevant types to fit the abilities. Use a new type only when you need to mention it in a card's instructions, like with [[Knight|Knights]] referring to themselves and [[Gathering]] with {{landmark|Defiled Shrine}}, or if it indicates something extra to do at setup like [[Looter]].

==== Draw ====
Having more cards in hand lets you do more, while letting you cycle through the deck; the latter means the card itself can be played more often (unless you trigger a re-shuffle). These reasons make drawing one of the more powerful mechanics; +cards are better than any of the other +vanilla bonuses. Making a draw card non-terminal lets drawn Actions be playable, so it's a lot more powerful (compare {{card|Smithy}} and {{card|Lab}}). Similarly, the presence of a {{card|Village}} in the kingdom makes a terminal draw card much more relevant.

==== Draw-to-X ====
Plus Cards let you expand your hand to however big, but draw to X liking smaller hands makes for an interesting way to make a deck or a way to counter handsize attacks. For cost, take how many cards you draw from a standard hand of 5 at the start of the turn as a guide; draw to 7 cards is 3 extra in hand, and {{card|Library}} and {{card|Cursed Village}} have extra effects on them to boost their cost to $5 (compare the latter to {{card|Watchtower|Watchtower's}} on-play effect).

==== Sifting ====
non-terminal cycling through the deck so you can choose from lots of cards, but usability is limited by hand size not improving; it would be a very strong card if hand size did improve (compare {{card|Cellar}} at {{cost|2}} to {{card|Warehouse}} at {{cost|3}} to {{card|Forum}} at {{cost|5}}). Generally good for moving junk cards along as an alternative to trashing or getting the order you play your cards in right.

==== Topdeck Grooming ====
Look at the top X cards, trash and/or discard them, and put the rest back. The official cards let you put these back in any order when you look at more than one; this is because it makes the accountability portion of the card much easier - no opponents can accuse you of trying to cheat if you're allowed to do it. These cards may slow the game down, as it involves several decisions each time you play topdeck groomer card.

==== Deck Discard ====
Put your deck into your discard pile. Usually used to allow players to look through their deck (and maybe trash or topdeck a card) without having to maintain the order of it. Can be thought of as drastic sifting, especially in junk games. 

==== Village ====
The ability to play more terminal Actions in a turn is crucial to a great many winning decks, so they will be picked up in the majority of games. Very rarely is a Village too bad in a game to not pick up, only if there's another Village better in the game. An interesting Village design isn't about when and when not to use it, but what kind of Action-heavy deck it makes.

==== Throne ====
Thrones can turn Actions with +1 Action into villages. Beyond this they're powerful for when you need the versatility between sometimes being drawing and sometimes payload. {{card|Throne Room}} effectively becomes a copy of the card you play next (unless it loses track of it), but {{card|King's Court}} adds more power than what 2 played cards could, which is why it's so strong. {{card|Procession}} can also add deck power. {{card|Royal Carriage}} gets around the problem of finding a target, but it doesn't work with self-moving cards like {{card|Madman}}. {{card|Scepter}} is non-terminal, but playing Actions at the buy phase limits them in various ways. {{card|Conclave}} is an interesting middleground to a traditional Throne design and a Village, while {{card|Imp}} is a middleground between a Throne and a {{card|Laboratory}}.

==== Non-Terminals ====
These are quick to resolve, since you can play many of them during a turn. Pay extra attention to how the card synergizes with itself, too.
All Treasure and Night cards are non-terminal.

===== Cantrips =====
Cards with +1 Card, +1 Action. The warnings for non-terminals apply more so here. Cantrips effectively replace themselves in your hand, so they're almost not a part of your deck unless there are effects looking for it as a card.

==== Virtual Coin ====
Non-Treasure effects with +{{cost|}}. Some decks like having these cards in them, like Tactician and draw to X, but generally it's easy to add +{{cost|}} onto cards whenever direct payload fits the rest of the card's abilities or when +Cards doesn't fit. Combining draw with +{{cost|}} is very strong, as illustrated by how hard Mercenary and Trusty Steed are to get. Making a variable +{{cost|}} effect creates a whole potential deck strategy.
These are non-terminal when players have {{project|Capitalism}}.

==== Plus Buy ====
This appears quite rarely amongst official cards, reason being that they would let you do too much and 3 piles would empty too often in the average game if more frequent.

==== Gainers ====
{{card|Workshop}} variants are great for building, being like +1 Buy, +{{cost|}} (gain a card costing (up to) $X), but unless you're looking to add lots of cards to the deck they lose usefulness later on. Gaining {{cost|5}}-cost cards is more potent than gaining {{cost|4}}-cost cards and Duchies are made accessible. Gaining a {{cost|4}} to hand is fairly strong and would probably make a $4.5 cost card by itself.

==== Trashing ====
These seem to feel generally more fun on average. They add extra functionality to the other cards in the kingdom by involving their cost.

==== Trash for Benefit ====
The ability to trash your starting Estates and Coppers, as well as other junk, is very powerful, the earlier it can be done the better.

==== On Gain, On Buy, On Trash ====
Effects like this have been the central concept of two expansions so far - [[Hinterlands]] and [[Guilds]]. [[Overpay]] is an elaborate (and usually scaling) on-buy effect. 
On Gain and On Trash abilities are (generally speaking) similar to Events, and can be designed accordingly. Things to bear in mind is gaining can happen outside of your turn ({{card|Swindler}}, {{card|Saboteur}}) and a card doesn't need to be in your hand, in play, or even yours at all to trash it ({{card|Lurker}}, {{event|Salt the Earth}}). A player may not even have the card at the end of the turn they bought it ({{card|Changeling}}), or it may not be where you expect it to be ({{card|Nomad Camp}}, {{card|Watchtower}}).

==== Vanishing ====
This is cards that either remove themselves from play like {{card|Embargo}} or {{card|Small Castle}}, or cards that return themselves to their pile like {{card|Experiment}} or {{card|Spoils}}. These cards are playable twice (or more) when Throned, but if their effect is contingent on their movement (like {{card|Madman}}), they won't work with [[Command]] cards.

==== Set Aside ====
Cards that are set aside aren't part of your hand or in play; if they came from your deck, they're still part of your deck. If they came from the supply, they exist outside of the supply now. [[Reserve]] cards were originally just set aside during playtesting for [[Adventures]] (likewise, the {{card|Native Village}} and {{card|Island}} mats were originally just setting aside cards during [[Seaside]] playtesting). Setting cards aside is useful for smoothing duration cards like {{card|Archive}} or {{card|Crypt}}, and for tracking out-of-turn reactions like {{card|Horse Traders}}.

==== Cost Comparisons ====
A thing to keep in mind with Dominion is there are three separate currencies to purchase things with - {{cost}} is by far the most common, but there is also {{debt}} and {{cost|P}}. Know how these compare (or don't) to each other. 

Consider the last line of {{card|Chariot Race}}: "If your card cost more, +{{Cost|1}} and +1{{VP}}."
When you play that and you reveal an {{card|Overlord}} and they reveal a {{card|Silver}}, despite your card's price number being higher, it's in a non-comparable currency. You don't take the {{cost|1}} and {{VP}}. If you reveal a {{card|University}} and they reveal a {{card|Silver}}, it likewise doesn't cost more. You're comparing apples and oranges. If you reveal {{card|Familiar}} and they reveal {{card|Silver}}, your card costs {{cost|P}} more, so you get the bonus.

This is where the big Otherwise comes in. Rather than handling each case individually - greater than, less than, equal to, orthogonal to - you can lump a bunch of those together into a "Do this if X; Otherwise, do that".

==== Type Rewards ====
When looking at another card's types and doing something (see {{card|Ironmonger}} or {{card|Sacrifice}}), you want to remember that there are multi-type cards, and that someone trashing their {{card|Harem}} with your souped-up Sacrifice card are going to get two things, not just one.

==== Choices ====
"Choose one" mechanics. Use whenever more flexibility is required. Make sure all the options are related in some way so the card has one overall function. Being a {{card|Governor|solo deck strategy is possible}}, provided that deck has distinct weaknesses. Try to also note how they feel together, as some combinations make for mundane, uninteresting choices. An example is 'choose one: +2 Actions; or + $2'. Do you go for Actions to see what more you can do with your deck, or just take what you can buy now because it's good enough?

Be aware this can also slow the game down; you may find the [[#Journey Token|Journey token]] more useful if there's only two choices and you want to force players to alternate between them.

==== Peeking: Reveal vs Look At ====
Use Look At when other players don't care what you're doing ({{card|Lookout}}) but Reveal when they need to know / hold you accountable ({{card|Patrol}}). Reveal is a keyword for {{card|Patron|Patron's}} reaction.

==== Exchange ====
There's untapped design space for exchange-for-benefit cards. A pitfall to bear in mind when using the exchange mechanic is it doesn't necessarily bring the game closer to finishing in the way trash-for-benefit does.

=== Research: Player Interaction ===
This section deals with player interaction concepts you may try to use when designing your cards. 

==== Two player vs 3+ players ====
An important thing to keep in mind is how your card will behave in games with only two players versus games with three or more players. Some official cards, like {{card|Jester}}, {{card|Noble Brigand}}, or {{card|Pirate Ship}}, become very powerful in 3+ player games. 

==== Racing ====
Racing is an inherent part of Dominion, in that it's a race to have the most points, and therefore probably the most {{card|Province|Provinces}}.
Other racing cards to look to for inspiration are {{card|Tournament}} and {{card|Emporium}}, as well as most [[Landmark|Landmarks]].

==== Tug of War ====
This concept is easiest to see in Artifacts & their cards, like {{card|Flag Bearer}} / {{artifact|Flag}}. The idea is to cause the "rope" (in this example, the Flag) to be fought over and change hands several times per game. There is lots of design space here.

==== Politics ====
A thing that Dominion generally doesn't do is political attacks. See [[#Targeting & Political Attacks|above]].

When a card wants you to interact with one other player specifically, the official cards have always gone with the player to your left ({{card|Advisor}}, {{card|Envoy}}, {{card|Possession}}).

==== Census cards ====
These are cards that look at other cards, and you do something based on that information.
There are lots of different incarnations of this. And example might be, "The player to your left reveals the top two cards of his deck. +{{cost}} equal to the number of victory points he reveals." Another one might be, "All players reveal their hands. The player with the least total treasure gains a Curse."

Sidestepping balance issues in these specific examples, these types of cards are unworkable because it's not always easy to quantify how many victory points or how much treasure you have in your hand. If only the base Victory cards are out, fine, but what if Gardens, {{card|Duke}}, {{card|Vineyard}}, or {{card|Fairgrounds}} is in play? You can't really calculate how much these are "worth" until the end of the game.

Treasure values are similarly nebulous. Technically, treasure isn't worth any coins at all until it's played. When a treasure card is played, only then does it yield some number of coins. In the case of the base treasures, this amount is always the same. (Well, almost. See {{card|Coppersmith}}.) But {{card|Bank}}, {{card|Philosopher's Stone}}, and {{card|Diadem}} vary, and {{Card|Potion}}'s yield isn't in coins at all.

Better approaches would be to count the number of Treasure or Victory cards, or look at the costs of those cards, or even count the number of types. In the case of using costs, you'll still have special cases in {{card|Philosopher's Stone}} and {{card|Vineyard|Vineyards}}, but many other Dominion cards ({{card|Salvager}}, {{card|Forge}}, {{card|Apprentice}}, etc) deal with (or ignore, in the case of Forge) Potion-based costs just fine.

==== Accountability ====
An example of such a card would be, "If this is in your hand at the start of your turn, you must play it immediately." The problem is that players can't be held accountable for following this rule. You'd have to have each player reveal his hand at the start of every turn, just so the other players can confirm that there is no copy of that card in hand to play. Otherwise it would be easy to keep the card in hand and secretly discard it underneath the other cards during clean-up.

That said, if you only intend to use such a card when playing with friends you trust, by all means, try an idea like this out. Otherwise, make sure your cards allow for accountability. Note Bureaucrat and Cutpurse, which provide such a mechanism.

Not all of the cards in the first edition base set are fully accountable - These were fixed in the [[Second Edition]]. Throne Room, Mine, and Moneylender all required you to do something with a card in your hand, but if you don't have a card of the correct type, they don't tell you to reveal your hand to prove it. ({{card|Treasure Map}}, from Seaside, was also like this.) Donald X. has expressed regret over Throne Room specifically; however, these cards were not problematic since the "fix" for them was to make their effects optional, rather than adding in accountability to the requirement. On a card whose effect needs to be mandatory (e.g., the aforementioned Bureaucrat and Cutpurse attacks), accountability is much more important, and you should make sure your own cards allow for it.

==== Passing ====
[[Pass]] as a keyword only appears on one official card, {{card|Masquerade}}. You'll want to probably pass things to the player on your left. There is probably some design space here, but less than you'd think - as with trashing attacks, players spend the whole game building their deck, and having to give it away can be demoralizing. For this reason, cards that force passing should probably always be terminal.

==== Pile Deterrent ====
Official cards like {{card|Embargo}} and {{card|Contraband}} deter or deny other players from using a Supply pile. You may want to avoid putting a card itself on top of a pile it doesn't come from - it can break self-gainers like {{card|Rats}} or {{card|Magpie}} in un-fun ways.

==== Cooperation ====
Or, giving your opponents something nice. This should be compulsory if it's included, something like a Duration that, while it's in play, when a player buys a Treasure, they get +1 Coffers - you get two turns with it in play, they get one, but you all get Coffers. Things that rely on goodwill from other players - say, a card that let you trade a card in your hand for a card in your opponents hand, if they want to trade - are dead on arrival, because not only is that a political card ("don't trade with Dave, he's winning!"), experienced players aren't going to want to trade because it's not to their benefit.
Official cards that include this generally do it in the form of +1 Card for your opponents - see {{card|Council Room}}, {{card|Governor}}.

=== Gameshaping ===
This section deals with cards that very drastically shape the game they're in. This isn't to say this is bad per se — official cards like {{card|Chapel}}, {{card|Baker}}, and any of the [[Heirloom]] cards do this as well — but these are things to be mindful of when designing a card.

==== Power Cards and Drawbacks ====
This comes up a lot, perhaps more than any other idea on this list. Examples are numerous. Basically you invent a cheap but powerful card and attach a negative {{VP}} penalty to try to balance it. On the surface, this idea presents an intriguing dilemma to the player: Do you take the hit to your score in the hopes that the extra power will enable you to overcome the deficit?

The problem is that there is essentially no way to make such a card balanced. In a kingdom where [[trashing]] is possible, the correct play is probably to buy these cards, reap their benefits, and trash them before the game ends, circumventing the penalty entirely. To balance the card in such a kingdom, the {{VP}} penalty would have to be quite steep, to offset the likelihood that the card will be trashed before the game ends. But if the {{VP}} penalty is steep enough to balance that situation, it will be way too steep in kingdoms without trashing available, as then the VP penalty would be too great to risk.

Many people try to correct this problem by adding a clause to the card such as "This card cannot be trashed" or "If this card is trashed, place it in your discard pile instead of the trash pile." This kind of special-case rule rubs me wrong (there's a section on special-case rules later), though it might be workable in this case. Another workaround people use is "When you buy this card, gain a Curse." Or, since the Curse pile can run out and gained Curse cards can be trashed, the concept of a "{{state|Miserable|curse token}}" is employed: "When you buy this card, gain X curse tokens." A curse token would be worth -1 {{VP}} at the end of the game, similarly to how VP Tokens are worth +1 {{VP}} at the end of the game.

Regardless, these solutions still come up short, although they're improvements on the original idea. The problem is that a power card can't be balanced with a fixed {{VP}} cost, for the simple reason that {{VP}} totals vary wildly from game to game, depending on the board. Dominion games can be won with 5 points and lost with 100. The difference between scores can be very small, meaning a -2 {{VP}} penalty could be decisive, or very large, making it insignificant.

A counterargument to this is that one of the basic strategic principles of Dominion is recognizing that every card is good in some situations and bad in others, so a card that is powerful sometimes and weak at other times is no problem at all. But this kind of card seems to be usually either dominant or suicidal and only rarely in between.

The best solution seems to be to cause a {{VP}} penalty to be incurred upon each USE of the card, rather than merely on the purchase of it. Then the {{VP}} penalty is directly proportional to the benefit you get from using it. In games with heavy-trashing, where the card would be used more often, the penalty is steeper. In no-trashing games, where the card would be used less often, the penalty is smaller.

Seemingly the two best ways to incur a penalty upon use of the card are (1) "Gain X curse tokens," and (2) "Gain a Curse. If you do...." The former incurs an irreversible VP penalty. The latter puts a stop to free power plays when the Curses run out. Both deal damage in proportion to the use you get out of the card.

=== Un-Dominion Ideas ===
These ideas shape the game in a way that makes it unfun or generally unrecognizable as canon-Dominion.
These all correlate to the [[#Specification|specification point]] that a card must give players a positive experience.

==== Junk is Junk ====
{{card|Estate|Estates}}, {{card|Copper|Coppers}}, and {{card|Curse|Curses}} are junk cards. Things that remove their junk card status ({{card|Coppersmith}}, {{card|Counting House}}, {{event|Inheritance}}, {{card|Baron}}) are either terminal or an expensive and limited once-per-game, and the cases where you want a curse in your deck are limited, and you generally don't want more than one even if you want exactly one ({{landmark|Defiled Shrine}}, {{landmark|Museum}}).

==== Infinity ====
Be careful when returning things to the Supply - you don't want the game to go on forever. 
Be aware of how your fan cards will interact with {{card|Champion}}, {{project|Capitalism}}, the [[Adventures tokens#Vanilla bonus tokens|Vanilla Bonus Adventures tokens]], and {{card|King's Court}}. While it's the jerk player who takes an infinite turn's fault for being unfun, it's also on you as the designer to jerkproof (and therefore infinityproof) your cards.

==== Drawn Out ====
You know that game of Monopoly that you played that one summer with your cousin that lasted a week and ended with a fistfight after you threw the Community Chest cards at them? Don't make Dominion that. Your card should help move the game towards the end of the game. Don't drag it out - while you might be thrilled at the prospect of a three hour dominion game, the other people you're playing against aren't, and at some point the player who's doing best will get an insurmountable lead. Don't make it miserable to play that out.

==== Special Case Rules ====
Before using a special-case rule, be very sure you cannot achieve the effect you're after any other way. Even then, think long and hard about whether your special-case rule will cause conflicts with other rules or cards.

For example, you might want to have a powerful card limited by the clause, "You may only play one copy of this card per turn." Fine, but what happens when {{card|Golem}} turns up two copies of it? Which card's rules get broken?

A way around this specific example is how {{card|Crossroads}} works - "If this is the first time you play this, " - or how {{card|Tormentor}} works - "If this is the only card in play,".

Other special case rules include the trash clause on {{card|Fortress}}, caring about odd/even quantities on {{card|Idol}}, and which actions you can replay on {{card|Scepter}} or {{card|Royal Carriage}}. Consider using these cards as templates when you're trying to do something "off script".

Generally it's better for cards to work within the rules of Dominion than to override them. Even if a special-case rule poses no problem with the current set of official cards, you never know if something in a future expansion will cause a conflict.

==== Resources Not Available ====
Examples of this would include "Gain an attack card", or "If you have at least three duration cards in play", or "You may trash up to 3 Curses", or "+{{cost|1}} for every dual-typed card in your hand." The problem with these cards is simply that if they show up in kingdoms without any of these types present, the card is useless.

You can still make such a card work if the card also has behavior that is sometimes worth buying anyway. This is the case with reaction cards such as {{card|Moat}}, {{card|Secret Chamber}}, and {{card|Horse Traders}}. In the absence of Attack cards in the kingdom, these may still be worth having for their other functions.

Another way to solve the problem is for the card itself to force the intended condition. For example, a card that specifically references {{card|Potion}} cards is fine if it carries a Potion-based cost, as then, whenever that card would be present, Potions would be present also. Similarly, "Choose one: Trash any number of Curses from your hand; or every other player gains a Curse" would work, as then you wouldn't need a separate cursing card to be present.

[[Split pile|Split piles]], [[Heirloom|Heirlooms]], and out-of-supply cards like {{card|Madman}} are other ways to force this synergy. However, cards that force synergy like that may be overly centralizing - you want an interesting kingdom where there's more than one winning strategy.

Another example of this kind of unworkable card would be something that has "-1 Buy" on it. I actually think that's a really cool idea; the problem is that it's dead in a kingdom with no +Buy cards.

Another example would be {{card|Diadem}}, a card whose behavior is based on having unused actions. Donald X. experimented with Diadem as a regular kingdom card but found it to be a dead card too often, as in many kingdoms there are no sources of extra actions. (But it works fine as a [[Prize]], where it's not taking up a whole kingdom pile.)

Still another example is a repeatedly proposed fan card that does only this: "+1 Card, +1 Action." Normally, this does nothing, as it merely replaces both the card slot and the action it uses up. But the justification for it is that it helps enable {{card|Conspirator}}, it lowers the price of Peddler, it can provide extra cards and actions with {{card|Throne Room}} or {{card|King's Court}}, it provides an extra unique card for {{card|Horn of Plenty}}, and so on. Yes, but the number of kingdoms with any of these cards in it is very small -- and in many of those, other cards will accomplish the same things. On the majority of boards, it's a dead pile.

== Mock Ups ==

=== Copy Editing ===
Now that you have the perfect fan card, maybe you want to print it for use in a live game. Well, first be aware that you do not have to print it to use it. If you want to use your card in a live game, you can write down what the card does on a piece of paper for reference, and then simply play with the blank cards that come with the game. If you have multiple sets of blanks, you can label them "A", "B", and so on, to differentiate them from each other. Then, for any given game, you can simply agree ahead of time what fan card each set of blanks refers to.

But if you want to print your cards properly, there are a couple ways you can do that. First, however, if you are a stickler for detail -- or intend to play with anyone who is -- you might want to note the formatting conventions listed below. Otherwise, skip to the next part for ways you can print your finalized artwork.

==== Vanilla Bonuses ====
The official order for vanilla bonuses on everything but treasures is as follows
# Cards
# Actions
# Buys
# +{{cost|}}
# Coffers
# Villagers
# +{{VP}}

On treasure cards, it's as follows
# {{cost|}} - ''Note there is no "+" when this is on treasure''
# Coffers
# Cards
# Actions
# Buys
# Villagers
# +{{VP}}

It sounds nitpicky, but all of the official cards adhere to this strict ordering and have consequently trained our eyes to use shortcuts to ingest the information. For example, if the first thing on a card is a boldface "+1 Buy," many experienced players will immediately understand this to be a terminal action without reading further -- because the "+1 Action," had it been present, would have appeared above the "+1 Buy" line. Adhering to the standard ordering will guard against players misreading your cards.

The only exception should be if the order of these vanilla bonuses needs to be different, as the order has a direct impact on the functionality of the card. Usually it does not, but if it does, then put the subsequent bonuses within the normal text of the card, as seen on the {{card|Cellar}}, {{card|Conspirator}}, and {{card|City}} cards.

=== Wording ===
The wording on Dominion cards is very simple and specific. Be as clear, concise, and consistent as you can with your wording. If your card is at all similar to anything an official card does, consult the official card and copy the relevant wording as appropriate.

As an example that illustrates how important precise wording is, notice how very deliberately {{card|Hunting Party}} tells you to "reveal cards from your deck" at first and only after you've found a card that isn't a duplicate do you "put it into your hand and discard the rest." Had it instead told you to "Reveal cards from your deck, discarding each one that is a duplicate of a card in your hand," then you could quite easily wind up in a situation where you are drawing your whole deck and discard pile over and over and over again, because there are no unique cards left in them.

One common omission in fan cards is specifying where cards must be when you use them. If a card's effect is to "Put any number of Treasure cards on top of your deck," where do those Treasure cards come from? From your hand? From play? From your discard pile? From the supply piles? It may sound pedantic to require this to be specified explicitly, but since different cards look for things in different places, the clarity is important.

Take care with your terminology, too. Certain words have specific meaning in Dominion. For example, don't use "purchase" if you mean "buy." Don't use "take" or "receive" if you mean "gain." As a good example for why the latter matters, note the difference between Ambassador and Masquerade. Ambassador uses the word "gain" and may therefore be countered by a Watchtower in hand. Masquerade does not, meaning that Watchtower cannot intervene.

==== Pronouns ====
Since [[Second Edition]], the official cards have switched to singular-they/their gender neutral language when player-pronouns have been required.

==== When To Use a Horizontal Line ====
A horizontal line on a Dominion card has a specific meaning: it separates what happens when you play the card from what happens at other times. {{card|Moat}} is a good example of this, as it separates the action ("+2 Cards") from the reaction ("When another player plays an Attack card....") Setup instructions, as seen on {{card|Young Witch}} and {{card|Black Market}}, are similarly divided.

"While in play" clauses are subtly important to separate. These can be found on {{card|Goons}}, {{card|Lighthouse}}, and {{card|Princess}}, among others. Here, the horizontal line is important because it serves as a reminder of what NOT to double with Throne Room or triple with King's Court.

Notice that there is no horizontal line between the "this turn" and "next turn" effects on Duration cards. Those are both things that happen by playing the card (and both get doubled with Throne Room and tripled with King's Court), so you don't want to separate them.

==== VP vs +VP ====
: 2{{VP}} means "This card is worth 2{{VP}} at the end of the game."
: +2{{VP}} means "Gain two victory tokens".

=== Fan Card Creation Tools ===
*[https://shardofhonor.github.io/dominion-card-generator/index.html Shard Of Honor's card template] - a fork of VioletCLM's card creator with additional functionality added.
*[https://shemitz.net/static/dominion3/ VioletCLM's card creator] - the original card creator
*[http://forum.dominionstrategy.com/index.php?topic=16622.0 thread discussing both card creators]

=== Layout ===
==== Fonts ====
On the official cards, the card's name and type are rendered in the "Trajan Pro" font. This is a commercial font; however, there is a very similar free alternative called "Optimus Princeps." Use the boldface version.

The interior card text is Times New Roman. Put the vanilla bonuses in boldface and everything else standard. If vanilla bonuses appear within a sentence, don't boldface them. (For reference, see Cellar and Conspirator.)

The card cost numbers are rendered in "Minion Pro," also a commercial font.  "Book Antiqua" is a similar free alternative.

==== Templates ====
On [https://boardgamegeek.com/thread/426860/fan-made-card-apprentice boardgame geek], you can find template images for the most common card types. For best results, use professional image editing software, like Photoshop. Microsoft Paint is probably not going to work for you.

Remember that even these card templates constitute proprietary artwork and are protected by copyright. Before using these images for any purpose, you may wish to research what constitutes fair use. Similarly, fair use issues may arise out of any additional artwork you add to these card templates.

==== Blank Cards ====
Need more blank cards? You can buy individual sets of blank cards. Searching Google Shopping will probably turn up a few different places to buy them. I buy mine at [https://boardgamegeekstore.com/products/dominion-blank-cards the board game geek store].

=== Printing ===
If you sleeve your Dominion cards anyway, then the best way to use your custom cards is to print copies out on regular paper and insert the slip of paper into a sleeve with a standard Dominion card (a blank, for example) also in it. Then they look like official Dominion cards from the back and handle the same way. This also preserves the reusability of the blank cards. Whenever you want to change which fan card you're using, you just swap out the slips of paper.

If you don't sleeve your cards, the alternatives aren't quite as clean. You can try using any of several online card printing services that will let you customize the fronts and backs of a set of playing cards. However, this poses two problems: 
#the thickness (320gsm), texture (flat + UV finish), and possibly color tinting of cards made this way is unlikely to match the look and feel of the official Dominion cards, so they may not feel quite right when shuffling; 
#Dominion uses a European/Skat standard card size, 59mm by 90mm. This is not available from most print-on-demand services like TheGameCrafter.com or DriveThruCards. 

I've had satisfactory results printing the cards out on Avery Clear Full-Sheet Labels, which are quite thin. You can buy them directly at avery.com, through a reseller like amazon, or in any number of office supply stores like Staples. Make sure you get the right product for your printer: if you have an Inkjet printer, only use the labels made for Inkjet printers; if you have a Laser printer, only use the labels made for Laser printers. Your local Kinkos/Fedex/Staples printer probably uses Laser printers for their 8.5x11/A4 paper and inkjet for their banners; they can probably also help you with finding suitable sticker paper

After printing your cards out, cut them out in dimensions slightly smaller than the Dominion card size, and apply them to the blank Dominion cards. This does make the cards a little thicker, but not in a dramatic or overly noticeable way. The texture of the colors will be a little different too - a consequence of most of the online prototyping tools and templates being RGB instead of CMYK - but certainly in the ballpark of what you need to communicate "hey, this is a Victory card, this is a Reaction card", etc. While not a perfect solution, I've found it to be a satisfactory one.

=== Take Pride in your Work ===
Well, this ended up being way longer than I expected! I hope this guide helps introduce the design field effectively and provides a convenient place where people can turn to for anything related to their card projects. If you know I'm wrong about something (some of the testing section might be very off) or you have suggestions as to improvements or additions, feel free to reply in [http://forum.dominionstrategy.com/index.php?topic=20045.0 this thread]. Or if you have anything you're stuck with in your project you can post it in this thread so others can read it too. I'll try to keep the guide up to date, but anyone can feel free to answer questions; just remember that everyone's Situation will be different, so put yourself in their position before answering, and make this a considerate and constructive space.

If you're enjoying yourself and proud of what you've created, ignore everything in this guide. Dominion is a game and having fun with it is all that ultimately matters.

Thanks for reading, and enjoy your Dominion!

== Sources ==
* [http://forum.dominionstrategy.com/index.php?topic=699.msg9668#msg9668 General Tips]
* [http://forum.dominionstrategy.com/index.php?topic=699.msg9668#msg9668 Common Pitfalls]
* [http://forum.dominionstrategy.com/index.php?topic=699.msg9669#msg9669 Myths About Card Prices]
* [http://forum.dominionstrategy.com/index.php?topic=699.msg9670#msg9670 Pricing Your Cards]
* [http://forum.dominionstrategy.com/index.php?topic=699.msg9671#msg9671 Formatting Your Cards]
* [http://forum.dominionstrategy.com/index.php?topic=699.msg9671#msg9671 Printing Your Card]
* [http://forum.dominionstrategy.com/index.php?topic=20045.0 Aquila's Up to Date Guide to Fan Card Creation]


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