Mikaeus, the Unhallowed + Grinding Station + Dread Tiller

Mikaeus, the Unhallowed

Grinding Station

Dread Tiller

How it works

1. Activate Grinding Station by tapping it and 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 and Grinding Station trigger.
4. Resolve the Dread Tiller trigger, putting a -1/-1 counter on it.
5. Resolve the Grinding Station trigger, untapping it.
6. Resolve the Grinding Station ability from step 1.
7. Repeat.