When you have multiple Zero Drives in play, do you need to track which units were banished by each specific Zero Drive, or can triggering one Zero Drive's play effect return units banished by any Zero Drive?

Question

Accepted Answer

Each physical instance of Zero Drive can only return cards it specifically banished; you must track which banished cards belong to which Zero Drive instance. This follows the rule that separate instances of an object or effect do not reference banished cards from other instances [427.3.a].

You must track which units were banished by each specific Zero Drive. When one Zero Drive's play effect triggers, it may only return the unit(s) that that same physical Zero Drive banished, not units banished by another Zero Drive [427.3.a] [427.3].

Player A has two physical Zero Drive permanents, Z1 and Z2, and each has banished one unit to Banishment when their effects resolved. Per the banish rules, those cards sit in Banishment but are associated with the object/effect that banished them [427.2] [427.3]. When Z1's play effect triggers and attempts to return a banished unit, check only the unit(s) that Z1 itself banished. Z1 cannot target or return the unit Z2 banished because separate instances do not reference other instances' banished cards [427.3.a]. If you later play another copy of Zero Drive (Z3) and it banishes a new unit, Z3 may only return the unit(s) it banished, and cannot return units banished earlier by Z1 or Z2 [427.3.a].

If a Zero Drive's wording does not explicitly reference "the cards it banished" but instead says something like "return a banished unit," the card text is ambiguous and you must consult that exact wording. The ruling above assumes the effect references the same object's banishments; if it doesn't, the interaction is not resolvable from the provided rules alone (assumption noted). If a banished card is moved out of Banishment by some other effect before a Zero Drive's play effect resolves, it is no longer available to that Zero Drive (it must reference the card while it's in Banishment) [427.2]. If an effect creates linked instructions that reference a banish performed by an earlier instruction, linked-ability rules may apply; you should follow linked instruction timing and dependencies per [393] if relevant.

The Core Rules say that "Cards and effects can refer to cards that were banished by the same object" [427.3] and then explicitly clarify that "Separate instances of an object or effect banishing cards do not reference other banished cards by objects of the same name or effects originating from cards of the same name" [427.3.a]. This means each physical Zero Drive is treated as its own source for the banished cards it created. Therefore, when a particular physical Zero Drive's play effect looks to return or play a card it banished, it can only access the card(s) that particular instance banished, not cards banished by a different instance of Zero Drive [427.3.a].

Additionally, banished cards are placed into the Banishment zone from their origin [427.2]; they remain in Banishment and associated with the object/effect that banished them for the purposes of effects that refer to "cards banished by" that object [427.2] [427.3]. The example in [427.3.a] directly parallels this situation: multiple copies of the same effect each track and can later retrieve only the card they individually banished. Thus you must track which units each Zero Drive banished, and resolving one Zero Drive's return effect cannot return a unit that another Zero Drive banished [427.3.a].