Mikaeus, the Unhallowed + Ashnod's Altar

Mikaeus, the Unhallowed

Ashnod's Altar

How it works

1. Activate Ashnod's Altar by sacrificing the creature with persist, adding CC.
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. Activate Ashnod's Altar by sacrificing the persist creature, adding CC.
4. When the persist creature dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
5. Repeat.