Game Actions may be the responsibility of up to one player. The player that performs the Game Action is responsible for it. Example: Cull the Weak is a spell that reads “Each player kills one of their units.” When the spell resolves, each player chooses a unit they control and kills that unit. They are responsible for the death of their own unit.
§ 411.1 Core Rules PDF (officieel)
§ 411 Responsibility
