Godhead of Awe + Ethereal Absolution

Steps

1. Godhead of Awe causes all other creatures to have base power and toughness of 1/1.
2. Ethereal Absolution gives all creatures your opponent control -1/-1.
3. Any creature that enters the battlefield under an opponent's control will do so as a 0/0 creature, and will die as a state-based action due to having zero or less toughness.