When are targets chosen for spells and abilities - when the spell is put on the chain or when it resolves?

Ruling: Spells and abilities with single targets must have valid targets chosen when the spell is put on the chain. Spells that require multiple choices (like "do X twice" effects) have those choices made on resolution.

Sequence:

• Single target spells (like Charm, Ride the Wind): Target is chosen when putting the spell on the chain, before it can be responded to
• Multiple choice spells (like Falling Star with "deal 3 damage twice"): Choices are made when the spell resolves
• Splitting effects: Targets are chosen when the spell is finalized on the chain

Nuances:

• If a single-target spell has no valid targets available, it cannot be put on the chain at all
• For multiple choice spells, opponents can respond to remove potential targets before resolution, forcing the caster to choose from remaining valid options (or their own units if no valid targets remain)
• Cards like Singularity choose targets on resolution, so you must counter them before resolution or the spell will resolve and pick targets