Editing In play

A card is said to be '''in play''' if it is in the '''play area'''—the location cards are put when you play them. Under ordinary circumstances, a card enters the play area when you play it, and leaves play when discarded during the [[Clean-up]] phase of that turn. [[Reserve]] cards also enter the play area when you [[call]] them.

There are a handful of cards, the [[Command variant|Command variants]], which instruct you to play a card ''without'' putting it in play. Some [[Throne Room variant]]s, which cause you to play the same card multiple times, can replay a card even if the first play of the same card caused it to be removed from the play area. In other cases, if a card cannot be moved into the play area (usually as a result of the [[stop-moving rule]]), it cannot be played.

Ordinarily cards leave the play area by being discarded during the [[Clean-up]] phase of the turn on which they enter play, though several exceptions exist:
* [[Duration]] cards, and Command variants playing Duration cards, remain in play until the Clean-up phase of the last turn on which they are expected to have an effect; [[Throne Room variant]]s playing Duration cards remain in play until the Clean-up phase of the turn when the Duration leaves play.
* [[One-shot]]s, [[Reserve]] cards, and certain other cards have instructions to remove themselves from play as a result of playing them.
* Some cards and card-shaped things have abilities that cause you to remove other cards from play before the Clean-up phase, or do something else with them in the Clean-up phase instead of discarding them: for example, {{card|Crypt}} sets aside [[Treasure]] cards from play when you play it, and {{card|Improve}} [[trash]]es a card from play during Clean-up instead of discarding it.

Some cards and [[card-shaped things]] have abilities that depend on what is in play at a given time. For example, {{card|Peddler}} changes its own [[cost]] depending on how many [[Action]] cards are in play during the Buy phase, and {{card|Changeling}} can only gain copies of cards that are in play.

== While-in-play abilities ==

Between {{set|Seaside}} in 2009 and {{set|Nocturne}} in 2017, a number of Dominion cards were released with abilities that are activated '''while the card is in play''', listed below a horizontal dividing line in the card text; these may be contrasted with "on-play" (or  "above-the-line") abilities, which are triggered by the card ''being played'', rather than by it being ''located in the play area''. Cards with while-in-play abilities were typically those with persistent effects on the game state that lasted for a period of time; [[Donald X. Vaccarino]]'s rationale in introducing the while-in-play mechanic was to facilitate tracking of these abilities, so players could simply inspect the cards that were visible in the play area to determine which abilities were in effect. 

However, players often found the rules for while-in-play abilities, and the differences between them and on-play abilities, confusing and counterintuitive—especially in cases where the same ability (such as [[cost reduction]]) was on-play for some cards (e.g., {{card|Bridge}}) and while-in-play for others (e.g., {{card|Highway|oi=2}}). As a result of this confusion, Donald X. eventually stopped introducing while-in-play abilities on new cards; and in the 2022 updates and revisions, all remaining cards with while-in-play abilities were either [[removed]] to be replaced with new cards in the [[second edition]] of {{set|Prosperity}}, or were revised to move the abilities above the line. 

=== Differences between while-in-play and on-play ===

Since while-in-play abilities begin to take effect when you play the card, it is easy to mistake them for abilities that are triggered ''by'' playing the card. However, while-in-play effects differ from on-play effects in several ways:
* If you play the same card multiple times on the same turn via a Throne Room variant, its "on-play" abilities happen each time you play it; but there is only one copy of the card in the play area, so its while-in-play abilities only happen once.
* If a card is played by a Command variant, it never enters play, so its while-in-play abilities never activate but its on-play effects do. Similarly, if a card is removed from play prematurely, its while-in-play abilities cease to operate, but any persistent on-play abilities remain in effect.
* {{card|Enchantress}} and [[Way]]s overrule the on-play abilities of an [[Action]] card, but leave the while-in-play abilities unchanged; {{card|Highwayman}} does the same for a [[Treasure]] card.

=== List of cards with while-in-play abilities ===

The following were revised in 2022 to turn the while-in-play abilities into on-play abilities:

* {{set|Seaside}}: {{card|Lighthouse|oi=3}}
* {{set|Prosperity}}: {{card|Quarry|oi=3}}, {{card|Hoard|oi=3}}
* {{set|Cornucopia}}: {{card|Princess|oi=2}}
* {{set|Hinterlands}}: {{card|Haggler|oi=2}}, {{card|Highway|oi=2}}
* {{set|Guilds}}: {{card|Merchant Guild|oi=2}}
* {{set|Adventures}}: {{card|Bridge Troll|oi=2}}
* {{set|Empires}}: {{card|Groundskeeper|oi=1}}
* {{set|Nocturne}}: {{card|Tracker|oi=1}}
* [[Promo]]: {{card|Sauna|oi=1}}

Three cards from {{card|Prosperity}}  with while-in-play abilities were [[removed]] in order to be replaced in the [[second edition]] of the expansion:

* {{card|Talisman}}, {{card|Royal Seal}}, {{card|Goons}}

=== Related abilities ===

No "while-in-play" abilities representing persistent effects remain. However, several cards still have below-the-line abilities that depend on the card being in play at a given time, or activate when the card is being discarded from play. These abilities are still subject to the rules differences noted above—in particular, when the following cards are played using a [[Way]], or subject to the effect of {{card|Enchantress}} or {{card|Highwayman}}, their below-the-line abilities are still in force.

* {{set|Dark Ages}}: {{card|Urchin}}
* {{set|Adventures}}: [[Traveller]]s
** {{card|Page}}, {{card|Treasure Hunter}}, {{card|Warrior}}, and {{card|Hero}}
** {{card|Peasant}}, {{card|Soldier}}, {{card|Fugitive}}, and {{card|Disciple}}
* {{set|Empires}}: {{card|Capital}}
* {{set|Allies}}: {{card|Merchant Camp}}, {{card|Tent}}
* [[Promo]]: {{card|Walled Village}}

The effects of the [[Trait]]s {{trait|Reckless}} and {{trait|Tireless}}, and the [[Artifact]] {{artifact|Horn}}, that move a card when it is discarded from play are not strictly speaking "below the line", but they are similarly not overruled by Ways, {{card|Enchantress}}, or {{card|Highwayman}}.

=== Donald X.'s evolving thoughts on while-in-play ===

Donald X. originally introduced while-in-play abilities for the sake of tracking persistent effects:
{{Quote|
|Text=
The purpose is tracking. "While this is in play" is always in play to show off that it's doing something (or isn't in play and so isn't doing anything). "This turn" effects like {{Card|Coppersmith}} / {{Card|Bridge}} might not be. It's not that I want to screw over {{Card|Throne Room|Throne}}/{{Card|Procession}} + {{Card|Highway}} or whatever, it's that {{Card|Procession}} + {{Card|Bridge}} makes you have to remember the Bridge effect.

It's fun to {{Card|Throne Room|Throne}} a {{Card|Bridge}} and so there's that. In general "while this is in play" is just better though.

Similarly {{Card|Conspirator}} looks at how many action cards you played this turn, but {{Card|Peddler}} counts the action cards in play. {{Card|Peddler}}'s approach is better; no tracking.
|Name=[[Donald X. Vaccarino]]
|Source=[http://forum.dominionstrategy.com/index.php?topic=5799.msg148785;topicseen#msg148785 Interview with Donald X.]
}}
At one point he contemplated revising earlier cards such as {{card|Bridge}} to use while-in-play wording, though he did not end up making this change. 
{{Quote|
|Text=
I would consider whether I like {{card|Bridge}} and {{card|Coppersmith}} as is, in their Throne-able glory, or if I would rather phrase them the way I think such stuff in general should be phrased, like {{card|Highway}} etc.
|Name=[[Donald X. Vaccarino]]
|Source=[http://forum.dominionstrategy.com/index.php?topic=3179.msg56362#msg56362 With my Dominion Time Machine...]
}}
Later, he discovered that players find while-in-play abilities more confusing than on-play abilities, and stopped using while-in-play abilities on new cards:
{{Quote|
|Text=
I switched from "this turn" to "while this is in play" because "while this is in play" has better tracking; you e.g. {{Card|Procession}} a {{Card|Highway}} and the card no longer in play no longer does anything, hooray. [In Renaissance] I switched back to "this turn" because it turned out people get more confused by "while this is in play."
|Name=[[Donald X. Vaccarino]]
|Source=[http://forum.dominionstrategy.com/index.php?topic=20566.msg857191#msg857191 Inventor wording]
}}
Finally, in 2022, all cards with "while this is in play" received errata to "this turn."
{{Quote|
|Text=
[While this is in play] also endlessly confuses players. Who are these players, someone is asking. Man. They're everywhere. Maybe you are in a bubble of rules experts, I dunno; they're really out there. They are surprised when {{Card|Throne Room|Throne}} - {{Card|Goons}} doesn't work and so on.

The {{Card|Highway}} cost-reduction feels just like {{Card|Bridge}}'s, but there are all these things that are actually different. This really honestly truly confuses people. Part of this for me was that I misphrased {{Card|Conspirator}} back when. It cares about cards you played; isn't it simpler to count the cards in play? Then you don't have to remember e.g. that {{Card|Mining Village}} that vanished. {{Card|Peddler}} does it the correct way. But well. Translating this to doing {{Card|Highway}} instead of {{Card|Bridge}} just endlessly confused people. I thought it was better for a few years there but eventually I saw the light. Again you may note a lack of such cards in recent expansions.

"This turn" seems straightforward in most cases. Some of these cards have other changes too; I didn't forget them. I'm not on a crusade to get rid of dividing lines; it's "while this is in play" that was specifically confusing.
|Name=[[Donald X. Vaccarino]]
|Source=[http://forum.dominionstrategy.com/index.php?topic=21326.msg894048#msg894048 The Why of the Errata]
}}
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[[category:Rules]]