If I cast Falling Comet targeting an enemy unit at a battlefield and my opponent reacts with Fight or Flight to move that unit, does Falling Comet fizzle or can I choose a new target?

Ruling: Falling Comet does not fizzle. It resolves with no effect, and you cannot choose another target. Riftbound does not have fizzling.

Sequence:

• Targets are declared and checked for legality on cast
• If the target becomes illegal (e.g., moved away from the battlefield), the spell still resolves
• Targets are checked again on resolution
• If the target is no longer legal, the spell resolves with no effect

Nuances:

• You cannot choose a new target after the original target becomes illegal