Editing Cost reduction

[[Image:Bridge.jpg|thumb|right|200px|[[Bridge]], a cost-reducing card.]]

'''Cost reduction''' is a recurring mechanic in Dominion.  Rather than directly fielding [[coin]], '''cost-reducers''' decrease the [[cost]] of cards, an effect which becomes more valuable with more buys or [[gainers]].  Typical cost reduction instructions follow this wording:

:''[All cards or some subset of cards] (including cards in players' hands) cost {{Cost|X}} less this turn.''

A general rule prevents costs from going below {{cost|0}}. Prior to the [[Dominion 2019 Errata and Rules Tweaks|2019 errata]], the stipulation "but not less than {{cost|0}}" was included in the card text of cost reducers themselves, rather than in the general rules, and that clause was never included in any of the cards of this category in {{Set|Menagerie}}.

Reducing a cost in {{Cost}} does not reduce a cost in {{Debt}} or {{P}}. Reducing the cost of cards does not affect the cost of [[Event|Events]] or [[Project|Projects]].

== Rules ==
There are no official rules for cost reduction in general. But there are official rules for cards that can change their own cost, which include {{Card|Peddler}}, {{Card|Fisherman}}, {{Card|Destrier}}, and {{Card|Wayfarer}}.
* When these cards change cost, all copies of them change everywhere, for all purposes. For example, when you {{Card|Remodel}} one of the cards, the changed cost is what matters, not the printed cost. When another player has an effect that cares what the cost of their cards is on your turn (such as the [[promo]] {{Card|Governor}}), they use the same changed cost that you do.
* Costs cannot go below {{Cost|0}}.
* [{{card|Peddler}},] {{Card|Destrier}} and {{Card|Fisherman}} are also affected by other things that change costs, like {{Card|Bridge}} (from {{Set|Intrigue}}). 
* Costs can change in the middle of resolving effects. The key thing is to follow card instructions in order.
** Example: You buy {{Card|Stonemason}} (from {{Set|Guilds}}). If you overpay {{Cost|2}} and have an empty discard pile, you could gain a {{Card|Fisherman}}, but not two copies of it, because after gaining one, Fisherman would cost {{Cost|5}}. If you overpay {{Cost|2}}, you could gain a {{Card|Sleigh}} and then a {{Card|Wayfarer}}, as {{Card|Wayfarer}}'s cost would then be {{Cost|2}}. You could not gain two {{Card|Wayfarer}}s, as you have not gained the {{Card|Stonemason}} yet - remember that "when you buy" rules happen before actually gaining the card. If you overpay {{Cost|6}}, you could gain {{Card|Destrier}}, but could not then gain a second {{Card|Destrier}}, as {{Card|Destrier}} would then cost {{Cost|5}}.
*** With recent errata to {{Card|Stonemason}}, this paragraph is outdated; here is an unofficial update: You buy {{Card|Stonemason}} and overpay {{Cost|2}}. Since you gain the {{Card|Stonemason}} before gaining 2 Actions costing {{Cost|2}}, {{Card|Fisherman}} would cost {{Cost|5}} and you'd be unable to gain it. If you overpay {{Cost|2}}, you can gain 2 {{Card|Wayfarer}}s, as gaining the {{Card|Stonemason}} means that {{Card|Wayfarer}} costs {{Cost|2}}. If you overpay {{Cost|5}}, gaining the {{Card|Stonemason}} means that {{Card|Destrier}} now costs {{Cost|5}}, so you can gain a copy of it, but when you do, {{Card|Destrier}} now costs {{Cost|4}}, so you can't gain a 2nd copy.
** Example: You play {{Card|Stonemason}} to trash a card. If you trash {{Card|Gold}}, you could gain a {{Card|Duchy}}, and then could gain a {{Card|Destrier}}, since it would then cost {{Cost|5}}. You could gain a {{Card|Duchy}} and then a {{Card|Wayfarer}} the same way. If you trash a {{Card|Silver}} and have an empty discard pile, you could gain a {{Card|Fisherman}}, but not a second one, as then your discard pile would have a card in it, the Fisherman you gained. If you trash a Destrier, you could first gain a {{Card|Duchy}}, which costs less than {{Cost|6}}; then you would have to gain a card costing up to {{Cost|5}}, as Destrier would now cost {{Cost|5}}.
** Example: If you use {{Card|Trader}} (from {{Set|Hinterlands}}) to trash a {{Card|Destrier}}, you will gain six {{Card|Silver}}s; first it checks the cost, then you gain that many {{Card|Silver}}s. Similarly you could trash a {{Card|Wayfarer}} for six {{Card|Silver}}s, and a {{Card|Fisherman}} for two or five {{Card|Silver}}s depending on whether or not your discard pile was empty when you trashed the {{Card|Fisherman}}.
** These examples all assume no other gains previously in the turn. A {{Card|Stonemason}} trashing {{Card|Estate}} could gain two {{Card|Destrier}}s if you gained 5 other cards first; if you gain a card costing {{Cost|4}} and then trash a {{Card|Wayfarer}} to {{Card|Trader}}, you will gain 4 {{Card|Silver}}s since it costs {{Cost|4}} then, and so on.

== List of cost-reducers ==
* {{Card|Bridge}} - the archetypal cost-reducer
* {{Card|Quarry}} - reduces [[Action]] cards by {{cost|2}}
* {{Card|Princess}} - reduces costs by {{Cost|2}}, but only one copy
* {{Card|Highway}} - [[cantrip]]
* {{Card|Bridge Troll}} - durational cost-reducer
* {{Event|Ferry}} - reduces a single Supply pile's cost by {{Cost|2}} on your turn
* {{card|Inventor}} - gains a card costing up to {{cost|4}} ''before'' its cost reduction kicks in
* {{project|Canal}} - reduces costs on your turn for the rest of the game
* {{ally|Family of Inventors}} - reduces cost of a supply pile of your choice, for everyone

== List of cards that can change their own cost ==
These cards have a base cost which can be changed by something that happens during your turn.  Of these, three are in the {{Set|Menagerie}} expansion
* {{Card|Peddler}} - cost is reduced by {{cost|2}} per Action card in play, but only during your [[buy phase]]
* {{Card|Destrier}} - cost is reduced by the number of cards you gained on that same turn
* {{Card|Fisherman}} - cost is reduced by {{cost|3}} if you have no cards in your discard pile
* {{Card|Wayfarer}} - cost is equal to the cost of the last-gained card, and can even become ''more'' expensive than its base price
{{Card|Animal Fair}}, also from {{Set|Menagerie}}, is an odd case: it can be bought for {{cost|0}} if you trash an Action card from your hand, but its numerical cost doesn't change as part of this effect.
== Strategy ==
Most cards that reference a specific cost in {{Cost}} do well with cost-reducers, as most such cards use the specific cost as an upper limit.  For example, {{Card|Workshop}} can gain any card costing up to {{Cost|4}}; without cost reduction, this effect is rather weak, but with four Highways in play, a Workshop can gain Provinces.  On the other hand, cards that give a scaling effect per cost in {{Cost}} of another card (most often [[trash for benefit]] cards) will do ''less'' well with cost-reducers, as their effect will be diminished, and cards that reference a cheaper card will give no effect if their cost has been reduced to {{Cost|0}}.  For examples, trashing a {{Card|Silver}} to an {{Card|Apprentice}} when you have Princess in play will only draw you one card, and with five Highways in play, {{Card|Band of Misfits}} can't do anything.

Since cost reduction affects cards but not Events, it is less useful for strategies that depend heavily on buying Events (or Projects).

==Gallery==
{{CardImage|Bridge}}{{CardImage|Bridge Troll}}{{CardImage|Inventor}}{{CardImage|Highway}}{{CardImage|Princess}}{{CardImage|Quarry}}{{LandscapeImage|Canal}}{{LandscapeImage|Ferry}}{{LandscapeImage|Family of Inventors}}

===Cards that can reduce their own cost===
{{CardImage|Destrier}}{{CardImage|Fisherman}}{{CardImage|Peddler}}{{CardImage|Wayfarer}} 

==Trivia==
===Cards that increase costs===
{{Quote
|Text= 
It's been tried multiple times. It's been given plenty of chances to somehow produce a fun working card.

Some of the issues - stacking, timing vs. cost reduction - can be solved, but the solutions take words, and you end up with something too complex. There's no special beauty to doing it that has pushed it into existence despite that.

Punishing buys is okay and there's some of that, e.g. {{Card|Embargo}}. {{Card|Contraband}} and {{Card|Delusion}} try out limiting buys. And {{Card|Peddler}} gives you the positive side, where a card costs more for your Remodels.
|Name=[[Donald X. Vaccarino]]
|Source=[http://forum.dominionstrategy.com/index.php?topic=19037.msg772189#msg772189 Ununtrashable Cards: The Complete List]
}}
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