How does Chakram Dancer work when I want to play her to base as a reaction?

Question

Accepted Answer

You may play Chakram Dancer as an Ambush (a Reaction) to a battlefield where you have units. Playing her creates a Chain/Pending Item; you (the player who played her) get priority; the play is finalized and then resolves, placing her and applying her “When you play me” effect to other units at that battlefield (granting Shield this turn and +1 while they're defenders). Cleanups will be scheduled as required but will not interrupt the finalization step. [333] [338.1.a.2] [338.1.a.4] [333.1] [319.3] [FAQ:unleashed#17]

You can play Chakram Dancer to the battlefield as a Reaction to a battlefield where you have units. That play creates a Chain and adds the card as a Pending Item; you are the first player with Priority for that Chain. The play is finalized (choices/costs/legal checks) and then resolves, which results in Chakram Dancer entering the battlefield and the “When you play me” effect applying to your other units at that battlefield (they gain Shield this turn and will get +1 while they are defenders). A Cleanup will be made Outstanding because a Pending Item was added, but cleanups do not interrupt finalization and do not occur while Chain Items are Resolving. [333] [333.1] [338.1.a.4] [338.1.a.2] [319.3] [321] [FAQ:unleashed#17]

Declare you are playing Chakram Dancer as an Ambush/Reaction to a battlefield where you control at least one unit (per the card's printed text). Playing the card creates a Chain and adds the card as a Pending Item to that Chain (a card-play Pending Item is created when you play a card) [333] [338.1.a.4]. Because you created the Chain, you become the first player with Priority for it [333.1]. A Cleanup becomes Outstanding as soon as a Pending Item is added to the Chain [319.3]. Per the rules and clarifications, Cleanups do not occur during Finalize; the FEPR process continues to Finalize (players make choices, pay costs, check legality) before any Cleanup is performed [FAQ:unleashed#17]. When the card-play Pending Item is finalized and then resolves, Chakram Dancer will enter the battlefield at that location (subject to any intervening effects), and its "When you play me" on-play effect will apply to other units at that battlefield. Those other units gain Shield this turn and will have +1 while they're defenders (as written on the card). After resolution, pending Cleanups will run as required (and per [321] a Cleanup will not interrupt resolving Chain Items; if the resolution created further Cleanup-qualifying events, additional Cleanups become Outstanding and run after the current Cleanup finishes).

If there are no other units at that battlefield when the on-play effect resolves, the "give your other units here Shield this turn" part does nothing (there are no qualifying targets). If units move away from or into the battlefield between finalization and the on-play effect resolving (due to other Chain Items or abilities), the Shield and the "+1 while they're defenders" will apply only to units that are actually at that battlefield when the on-play effect resolves (this follows from the general model that effects apply at resolution; specific targeting/timing rules for on-play triggers are not present in the provided context). If some other effect prevents Chakram Dancer from entering the battlefield or replaces the play with a different event, then its "When you play me" effect may not trigger or may be affected; the provided Core Rules excerpt does not include replacement/intervening-effect rules for play, so that is an assumed standard interaction. The rules excerpt does not define Shield's exact behavior or duration beyond the card text, so anything that references Shield's interaction with damage, blocking, or recalls is not covered here.

Short answer: You may play Chakram Dancer to a battlefield you occupy as a Reaction (Ambush). Doing so creates a Chain and adds the play as a Pending Item; you are the first player with Priority for that Chain; you finalize the play (make any choices/payments/check legality) and then the play resolves, putting Chakram Dancer onto the battlefield and causing the on-play text to affect your other units at that battlefield (they gain Shield this turn; they get +1 while they're defenders). The relevant rules: whenever you play a card, a Chain is created [333] and the card is added as a Pending Item [338.1.a.4]; Reaction cards are considered legally timed plays under the exception for Reaction cards [338.1.a.2]; the player who created the Chain is first with Priority [333.1]; adding a Pending Item to the Chain makes a Cleanup Outstanding [319.3], but Cleanups do not interrupt the Finalize step and cannot occur while Chain Items are Resolving [FAQ:unleashed#17] [321].

What actually happens in practice (ordered): you announce the Ambush play, the game creates the Chain and the play becomes a Pending Item [333] [338.1.a.4]; you (the chain creator) get Priority [333.1]; Finalize proceeds (decisions/payments/legal checks) and then Resolve proceeds; on resolution Chakram Dancer enters the battlefield and the "When you play me" effect is applied to your other units at that battlefield — those units get Shield for the turn and will have +1 while they are defenders (as the card text states). Any Cleanups that were made Outstanding when the Pending Item was added will occur at the next allowed point between FEPR steps [319.3] [FAQ:unleashed#17].

Notes/assumptions: The provided Core Rules context does not include a formal definition of Ambush or the full procedural text for on-play triggers, nor Shield specifics. I used the defensible interpretation that Ambush/Reaction makes the card a legally timed play (per [338.1.a.2]) and that the on-play effect applies to units present at the time that effect resolves. If you need a ruling about a very specific timing interaction (for example, another effect responding on the Chain that moves units before the on-play effect resolves), give me that precise sequence and I will walk through it step-by-step using the Chain and Cleanup rules.