Rule 429.1.a.1

Active Kill is when the action is taken when instructed by a game effect or as a cost for a card or ability.

• 429.1.a.1.a This is referred to as a Kill Instruction.
• 429.1.a.1.b When a unit with a Deathknell or other ability that triggers on its own death is to be put in the Trash due to a Kill…

Official Core Rules