Can Retreat be cast on a champion that was played from the chosen champion zone (rather than from hand)?

Question

Accepted Answer

Yes. Retreat can be cast on a Chosen Champion that was played from the Champion Zone as long as that champion is currently a unit on the board (a battlefield). If the Chosen Champion is still in the Champion Zone (i.e., hasn't been played to the board), Retreat cannot target it.

Retreat may target and return a Chosen Champion that was played from the Champion Zone once that Chosen Champion is on the board, because it is then a unit on the board and thus a valid target for “a friendly unit.” If the Chosen Champion remains in the Champion Zone (not on the board), it is not a valid target for Retreat.

Confirm the Chosen Champion has been played from the Champion Zone and is currently a unit on the board (a battlefield) [355.9.a.1] [103.2.a.1]. Play Retreat as a Reaction and choose that friendly unit as the target (a 'friendly unit' refers to a unit on the board) [355.9.a]. When Retreat resolves, return the targeted unit to its owner's hand and that player channels 1 rune exhausted (follow the card text). If the unit had left to a non-board zone before Retreat finished resolving, it would no longer be the same object and thus would not be a legal target [359.3.e.4].

If the Chosen Champion was never played to the board and remains in the Champion Zone, Retreat cannot target it because 'unit' in spells refers to objects on the board unless otherwise stated [355.9.a.1]. If the Chosen Champion was played to the board but then moved to a non-board zone (e.g., trash or exile) before Retreat resolves, it ceases to be the same game object and is no longer a legal target [359.3.e.4]. If a card or effect grants a special rule that specifically prevents that particular champion from being returned to hand, that override would change the interaction; no such override is present in the provided context.

A 'Chosen Champion' begins the game in the Champion Zone [103.2.a.1] [113]. However, once that Chosen Champion has been played to a battlefield, it exists on the board as a unit. The targeting rules define 'unit' (and 'gear' and 'rune') as referring to objects on the Board unless specified otherwise [355.9.a.1] and state that a valid target for a spell is typically a permanent on the board [355.9.a]. Retreat reads 'Return a friendly unit to its owner's hand,' which targets a unit on the board. Therefore, if the Chosen Champion has been played from the Champion Zone and is currently on the board, it is a legal target for Retreat. If the Chosen Champion is still in the Champion Zone (not on the board), it is not a unit on the board and thus not a valid target for Retreat. Finally, be aware of zone-change timing: if the unit moves to a non-board zone before Retreat resolves, it is no longer the same game object and is not a legal target [359.3.e.4].