When you cast Rain or Falling Star, do you choose targets one-by-one or all at once? If an opponent uses Retreat on one of the targets, do you select a new target for that reflexive trigger?

Ruling: You choose all targets at once after the spell resolves, but each target is for a separate item on the chain. You never select new targets under any circumstances - targets are chosen when the item enters the chain and cannot be changed afterwards.

Sequence:

• Cast the spell (e.g., Rain)
• If the spell resolves, all 6 reflexive triggers are put on the chain together
• Each trigger is a separate item on the chain with its own target
• Opportunities to respond exist between each trigger

Nuances:

• If a target becomes invalid (e.g., due to Retreat), you do not choose a replacement target
• Targets are locked in when items enter the chain and cannot be changed