When do you select targets for spells like Falling Star vs Void Seeker, and what happens if the original target becomes invalid?

Ruling: Spells with "do this" wording (like Falling Star and Icathian Rain) use reflexive triggers that target after the spell resolves, so if the original target becomes invalid you must select a new target (even your own units if necessary). Spells without "do this" wording (like Void Seeker) target when first played, before the spell resolves.

Sequence:

• For reflexive trigger spells: Cast the spell → opponents can respond → spell resolves creating reflexive triggers → select targets for each trigger → triggers resolve
• For normal spells: Select target when casting → opponents can respond → spell resolves with damage/effect

Nuances:

• With reflexive triggers, if a target is removed (e.g., by Retreat/Gust) before you select targets, you must choose a new valid target
• Reflexive triggers are identified by "do this" wording on the spell card