If a 6 might unit with 3 damage markers from Hextech Ray is targeted by Smoke Screen and dies during cleanup, which spell is considered the source of the kill?

Ruling: Neither spell receives credit for the kill. The spell that resolved immediately prior to cleanup must have applied damage markers to be considered the source of the kill.

Sequence:

• Hextech Ray applies 3 damage markers to a 6 might unit
• Smoke Screen targets the unit but does not apply damage markers
• Unit dies during cleanup
• No spell receives responsibility for the kill action because Smoke Screen (the most recent spell before cleanup) did not apply damage