All creatures your opponents control will have base toughness -1, and die as a state-based action due to having 0 or less toughness unless there is another effect increasing its toughness.
Whenever a creature enters the battlefield under an opponent's control, it will have base toughness -1, and die as a state-based action due to having 0 or less toughness unless there is another effect increasing its toughness.
Results
Reduce each opposing creature's toughness to zero.
Creatures opponents control die upon entering the battlefield.