When a spell like Icathian Rain deals damage to multiple units that would die from that damage, do they die simultaneously or in sequence, and can their 'When something dies' abilities trigger?

Ruling: When a spell deals damage to multiple units, all damage is dealt first, then the spell goes to trash, then the cleanup step runs and all units with damage >= might die simultaneously. Their 'When something dies' abilities cannot trigger because units that die at the same time do not see each other's death abilities.

Sequence:

• Spell deals all its damage
• Spell goes to trash
• Cleanup step runs
• All units with damage >= might die simultaneously

Nuances:

• Units dying simultaneously do not see each other's 'When something dies' abilities