If I have hidden a Flight or Fight and my opponent casts Hidden Blade, can I react to move my unit back to base and save it? Or does the Hidden Blade effect still happen even though my unit would not be at a battlefield?

Question

Accepted Answer

If you can play a Reaction that moves your unit to base in response to Hidden Blade before it resolves, the unit will not be killed. Hidden Blade must target a unit at a battlefield when it’s put on the chain, but if that targeted unit is moved to your Base (still on the board) before resolution, the spell’s instruction “Kill a unit at a battlefield” cannot be carried out against it.

You can react to move your unit to Base to save it from Hidden Blade as long as the move happens before Hidden Blade resolves. Hidden Blade still targeted the unit when cast, but because the kill instruction requires the unit to be at a battlefield at resolution, it cannot kill a unit that is on Base.

Opponent plays Hidden Blade and, as part of finalizing it on the chain, they choose a unit at the battlefield as its target (this is required to put the spell on the chain) [355.8] [811.1.d.2]. You may respond with a Reaction that moves that targeted unit to your Base (if you have such a Reaction and it is legal to play in response). If you successfully move the unit to Base before Hidden Blade resolves, the unit is still the same game object on the board so it remains the spell's target, but it no longer fulfills the spell's location requirement "at a battlefield." That means the kill instruction cannot be executed against it on resolution [359.3.e.3] [359.3.e.11] [FAQ:unleashed#20]. If the unit instead changed to a non-board zone (hand, trash, banish), the targeting relationship is severed and Hidden Blade cannot kill it; checks that depended on it as a board object would return null [359.3.e.12] [FAQ:unleashed#22].

If your move-to-Base effect happens during resolution of Hidden Blade after the point where the spell's only instruction has already been executed, it's too late — the timing matters. You must move the unit before the spell resolves. If the move sends the unit to a non-board zone (hand, trash, banish), the unit is no longer the same game object on the board and the targeting relationship is severed; the spell cannot affect it and any checks that referenced its on-board properties become null [359.3.e.12]. If Hidden Blade was not played from Hidden (i.e., it was played normally), it still targets a unit at a battlefield when cast and the same interaction applies: moving the unit to Base before resolution prevents the 'at a battlefield' kill instruction from being carried out [355.8] [359.3.e.11]. If your "Flight or Fight" effect cannot legally be played in response (not a Reaction or not playable at that time), you cannot use it to save the unit. This ruling assumes the move is a legal response.

When Hidden Blade is played it must choose a target that is "a unit at a battlefield" in order to be put on the chain [355.8] [811.1.d.2]. That targeting relationship is created and is maintained while the spell is on the chain so long as the targeted game object remains on the board [FAQ:unleashed#22] [359.3.e.3]. However, whether Hidden Blade can actually "Kill a unit at a battlefield" when it resolves depends on the unit's location at resolution. If the targeted unit is moved to your Base (still a board zone) in response before Hidden Blade resolves, it no longer fulfills the specific location restriction "at a battlefield." The spell still remembers the unit as its target, but the instruction requiring the unit be at a battlefield cannot be executed, so the kill does not happen [359.3.e.11] [FAQ:unleashed#20]. If instead the unit is moved to a non-board zone, the targeting relationship is severed and any checks about the target that require it to be on the board return null, so the spell cannot kill it [359.3.e.12]. Therefore, provided you can legally play your move-to-Base effect in response to Hidden Blade, you can save the unit by moving it to Base before resolution. If you cannot play the effect in response, you cannot save it.