How does Icathian Rain work when targeting units that die mid-resolution or are saved by Zhonya's Hourglass?

Ruling: When Icathian Rain resolves, you immediately put 6 triggers on the stack and select all targets at that time. Each trigger deals damage to its selected target regardless of where that unit is on the board (battlefield or base), and you cannot retarget mid-resolution.

Sequence:

• Icathian Rain resolves and creates 6 triggered abilities on the stack
• You select a target for each of the 6 triggers at this time
• Each trigger resolves in order, dealing damage to its selected target
• If a unit dies and is saved by Zhonya's Hourglass, it is recalled to base but remains the same unit
• Remaining triggers still affect that unit even though it's now at base

Nuances:

• Situation 1 was played incorrectly - the opponent should have paid Deflect for only some triggers and let the rest whiff, rather than recycling 6 runes for each effect
• Icathian Rain can target units anywhere on the board (battlefield or base), unlike some spells that only target units at specific locations
• A unit saved by Zhonya's Hourglass never dies and is considered the same unit object, so it retains modifiers and can still be targeted by previously-assigned triggers
• If a unit were banished and replayed, it would be a new object and could not be targeted by the original triggers