When Icathian Rain creates 6 reflexive triggers against two units (3 might and 4 might) and the opponent has Zhonya's Hourglass hidden, can the remaining triggers still kill a unit that was moved to base by Zhonya's, and when should Zhonya's be activated?

Ruling: All targets for Icathian Rain's 6 reflexive triggers must be chosen when the triggers are added to the chain, before any resolve. Zhonya's Hourglass should be activated right before the trigger that would deal lethal damage to the unit you want to save. In the scenario with a 3 might and 4 might unit, the defender can always save one unit but not both - if the attacker targets the 4 might unit with 4 triggers, that leaves only 2 triggers for the 3 might unit (which the defender can save), and vice versa.

Sequence:

• Icathian Rain is played (reaction window)
• Icathian Rain resolves, creating 6 reflexive triggers
• Attacker chooses targets for all 6 triggers
• Reaction window occurs after all targets are chosen but before any triggers resolve
• Each trigger resolves one at a time with a reaction window after each
• Zhonya's Hourglass should optimally be revealed right before the trigger that would kill the targeted unit

Nuances:

• Once targets are chosen, the defender knows which unit can be saved and which cannot based on how many triggers targeted each unit
• Zhonya's must be activated before lethal damage is dealt (as a replacement effect)
• After a unit is moved to base by Zhonya's, remaining triggers targeting it still resolve and can kill it again in the base
• There is a reaction window after all 6 targets are selected but before any damage is dealt, in addition to windows after each individual trigger