If an opponent plays Falling Comet targeting a unit at a battlefield, and you react with Flash to move the unit to base, does Falling Comet still resolve and destroy the unit?

Ruling: If you move your unit back to base with Flash, Falling Comet will not have a valid target on resolution and will not deal damage to the unit.

Nuances:

• Falling Comet specifies "at a battlefield" as part of its targeting requirement
• When the target is no longer at a battlefield upon resolution, the spell loses its valid target