The Scales of Anubis

Each creature on the battlefield has Soulsearch X, where X is its toughness minus its power.
Creature can't have negative Soulsearch values.
Whenever a creature dies, if it had Soulsearch 0, exile it and its controller loses 3 life.
On one side, your heart, on the other, the a feather of truth. The worthy shall pass, but and the others shall perish.