If Viktor, Leader and another unit (like Watchful Sentry) both die simultaneously from the same source (like Stormbringer dealing damage to multiple units), does Viktor's triggered ability see the other unit die?

Ruling: Viktor does not see other units die when they die simultaneously with him. All units die during cleanup after the spell resolves, and Viktor must be on the board when triggered abilities are added to the chain for his ability to activate.

Sequence:

• Stormbringer deals damage simultaneously to all selected units
• The spell finishes resolving
• Cleanup occurs, removing all units with lethal damage (including Viktor and the Sentry)
• Triggered abilities would be added to the chain after cleanup
• Viktor is no longer on the board at this point, so his ability cannot trigger

Nuances:

• "When a unit dies" means "after a unit dies" - the unit must still be on the board when the ability would trigger
• Even if Viktor sees a unit die, he needs to be on the board by the time priority is regained for the triggered ability to activate
• This applies even if Viktor dies slightly after another unit during the same spell resolution (e.g., "Kill a unit, then deal damage to Viktor") - both are removed during the same cleanup step