When Zhonya's Hourglass interacts with reflexive spells (like Icathian Rain or Falling Star), can a unit be killed twice - once triggering Zhonya's, then again by remaining reflexive triggers?

Ruling: Yes, a unit with Zhonya's Hourglass can be killed twice by reflexive spells. When Zhonya's replaces the first death, the unit never leaves the board and remains a valid target, so remaining reflexive triggers can still deal damage and kill it again.

Nuances:

• If the unit gets recalled to base by Zhonya's, it may become an invalid target for spells with "battlefield only" targeting restrictions, but Icathian Rain and Falling Star don't have such restrictions
• Spells that fizzle due to invalid targets resolve as much as possible, but the specific outcome depends on the spell (some effects like draw may still resolve, others may not if they can't determine a controller)