Gisa, Glorious Resurrector

If a creature an opponent controls would die, exile it instead.
At the beginning of your upkeep, put all creature cards exiled with Gisa, Glorious Resurrector onto the battlefield under your control. They gain decayed. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Ghoulcaller Gisa

{B}, {T}, Sacrifice another creature: Create X 2/2 black Zombie creature tokens, where X is the sacrificed creature's power.