Mikaeus, the Unhallowed + Altar of Dementia

Mikaeus, the Unhallowed

Altar of Dementia

How it works

1. Activate Altar of Dementia 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 Altar of Dementia ability.
4. Activate Altar of Dementia 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 Altar of Dementia ability.
7. Repeat.