Mikaeus, the Unhallowed + Viscera Seer + Wingrattle Scarecrow

Mikaeus, the Unhallowed

Viscera Seer

Wingrattle Scarecrow

How it works

1. Activate Viscera Seer by sacrificing Wingrattle Scarecrow.
2. When Wingrattle Scarecrow 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 Wingrattle Scarecrow.
5. When Wingrattle Scarecrow 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.