Why does a Poro with Zhonyas die to Falling Star's two instances of 3 damage, when it would survive Icathian Rain's six instances of 2 damage?

Ruling: Falling Star creates two separate reflexive triggers that resolve independently with their own clean-up steps. When the first trigger resolves, the Poro dies and Zhonyas saves it, but then the second trigger resolves and kills the Poro again.

Sequence:

• First Falling Star reflexive trigger resolves, dealing damage to the Poro
• Poro dies and Zhonyas saves it
• Second Falling Star reflexive trigger resolves, dealing damage to the Poro
• Poro dies (Zhonyas already used)

Nuances:

• This rule changed in a more recent FAQ, so older answers about similar interactions may not be accurate
• Each reflexive trigger has its own clean-up step, unlike abilities that deal all damage in a single resolution