Can an opponent play a reaction card (like Stupefy) in response to a 'when you play me' triggered ability on a unit (like Faithful Manufactor)?

Question

Accepted Answer

Yes. An opponent may play a Reaction (for example, Stupefy) in response to a triggered “When you play me” ability from a unit like Faithful Manufactor. However, the Reaction can only affect legal targets that exist at the time it is played — it cannot target or change the token that the trigger will create until that token actually exists. If the Reaction makes the trigger's instruction impossible to carry out when the trigger resolves, that instruction will be ignored as appropriate.

An opponent may cast a Reaction while the triggered “When you play me” ability from Faithful Manufactor is on the chain (i.e., in response to that trigger) [813.1.c.1] [FAQ:unleashed#2]. They may only target objects that legally exist at the time they play their Reaction; they cannot target the 1 :rb_might: Recruit token before it is created. If, by the time the trigger resolves, its instruction has no legal targets or cannot be executed, that instruction will be ignored or the parts that cannot be executed will be ignored per the usual resolution rules [359.3.e.5] [359.3.e.6].

You play Faithful Manufactor; its "When you play me, play a 1 :rb_might: Recruit unit token here." trigger is generated and becomes a pending triggered ability on the chain (see the trigger/finalization discussion) [FAQ:unleashed#2]. Before that triggered ability resolves, players may play Reactions because Reactions can be played during Closed States/on the chain [813.1.c.1] [813.2]. An opponent may cast Stupefy in response, but Stupefy can only target a legal, existing unit at the time it is cast. The 1-might Recruit token has not been created yet, so it cannot be targeted by that cast of Stupefy. If the opponent targets an existing legal unit (for example, Faithful Manufactor itself or another unit) the Stupefy will resolve first, applying its effects to that legal target and drawing a card. After all Reactions and responses finish resolving, the pending triggered ability from Faithful Manufactor will then resolve and create the 1 :rb_might: Recruit token (provided the instruction is still executable). If, by that time, the trigger's instruction has no legal targets or otherwise cannot be executed, the relevant instruction(s) are ignored [359.3.e.5] [359.3.e.6].

Trying to target the recruit token with a Reaction played in response to the trigger: not allowed because the token doesn't exist yet. You must wait until after the trigger resolves (the token exists) to target it [FAQ:unleashed#2]. If a Reaction moves or removes something such that the trigger's instruction has no legal way to execute when it resolves (for example, the battlefield is no longer legal for placing the token), that instruction will be ignored per [359.3.e.6]. If a Reaction changes the target status of an already-chosen target (but the target remains on the board as the same game object), target-relationships created earlier are generally maintained while on the chain; if the target merely becomes temporarily illegal but later becomes legal again, it can still be affected [FAQ:unleashed#22] [359.3.e.3]. (Note: the FAQ about Alpha Strike in [FAQ:unleashed#22] explains that target relationships persist while the object remains the same board object.) If the triggering object itself is moved to a non-board zone before the trigger finalizes in a way that makes fulfillment impossible, follow the normal rules about targets and resolution — e.g., things that change to a non-board zone can sever relationships and make instructions impossible [359.3.e.4].

Reactions are explicitly allowed to be played while triggered abilities are pending: Reaction grants a card the permission to be played during Closed States on any player's turn [813.1.c.1] and is not limited to only Closed States or Showdowns [813.2]. When you play Faithful Manufactor, its "When you play me" ability becomes a triggered ability placed on the chain and will be finalized/resolved after players have the opportunity to respond during the usual finalization/window process described for triggers [FAQ:unleashed#2]. During that window an opponent may cast a Reaction such as Stupefy (which the card text marks as a Reaction and so is playable any time) in response to the pending trigger. However, a spell can only target legal objects that exist at the time the spell is cast. The 1 :rb_might: Recruit token created by Faithful Manufactor's trigger does not exist yet while the trigger is pending, so Stupefy cast in response cannot target that token. If the opponent instead targets an existing unit (including possibly the played Faithful Manufactor itself), that Reaction resolves first and applies its effects. After all Reactions and responses resolve, the pending triggered ability from Faithful Manufactor will then resolve and create the token if its instruction is still executable. If the trigger's instruction cannot be carried out because targets are no longer legal or the necessary conditions no longer exist, the instruction(s) that can't be followed are ignored per the resolution rules [359.3.e.5] [359.3.e.6].