When playing Icathian Rain, do you assign all damage targets before the opponent can respond, or can you assign 2 damage at a time?

Ruling: When Icathian Rain resolves, it creates six separate items on the chain, each dealing 2 damage. You must choose all targets at once when the spell resolves, before any of the damage triggers begin resolving.

Sequence:

• Cast Icathian Rain
• Opportunity for Reactions
• Rain resolves, creating six items on the chain, each requiring a target (all targets chosen at this point)
• Opportunity for Reactions before the damage triggers start resolving
• Each damage trigger resolves individually with priority windows for Reactions between each resolution

Nuances:

• Opponents can respond with Reactions (like Discipline) after all targets are chosen but before the damage resolves
• Players could respond to the triggers being placed on the chain, but all targets will already be chosen at that point