Mikaeus, the Unhallowed + Viscera Seer + Dread Tiller

Mikaeus, the Unhallowed

Viscera Seer

Dread Tiller

How it works

1. Activate Viscera Seer by sacrificing Dread Tiller.
2. When Dread Tiller dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
3. When Dread Tiller enters the battlefield, it triggers, putting a -1/-1 counter on it.
4. Resolve the Viscera Seer ability
5. Repeat.