If Hidden Blade kills the Recruit in response to Falling Star being played, does Falling Star fizzle or must Kaisa target her own 3 Might unit?

Ruling: Falling Star must target Kaisa's own unit. The spell does not fizzle (spells always resolve in Riftbound), and because Falling Star uses a reflexive trigger that chooses targets after the spell resolves, the Recruit is already dead when targets must be selected.

Sequence:

• Falling Star is played
• Hidden Blade is played in response, killing the Recruit
• Hidden Blade resolves
• Falling Star resolves and creates a reflexive trigger
• The reflexive trigger chooses targets (at this point the Recruit is dead)
• Kaisa must select her own 3 Might unit as the target

Nuances:

• This interaction is specific to spells with reflexive triggers like Falling Star and Itachian Rain that choose targets after the spell resolves
• Other spells that deal damage directly choose targets when the spell is played and would have no effect if the target is killed in response