Mikaeus, the Unhallowed + Spawning Pit

Mikaeus, the Unhallowed

Spawning Pit

How it works

1. Activate Spawning Pit by sacrificing the creature with persist.
2. When that creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Resolve the Spawning Pit ability.
4. Activate Spawning Pit by sacrificing the persist creature.
5. When the persist creature dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. Resolve the Spawning Pit ability.
7. Repeat.