Mikaeus, the Unhallowed + Viscera Seer + Gravelgill Axeshark

Mikaeus, the Unhallowed

Viscera Seer

Gravelgill Axeshark

How it works

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