Mikaeus, the Unhallowed + Cinderhaze Wretch

Mikaeus, the Unhallowed

Cinderhaze Wretch

How it works

1. Activate Cinderhaze Wretch's second ability by putting a -1/-1 counter on it, untapping it.
2. Repeat step 1 until Cinderhaze Wretch dies as a state-based action due to having zero toughness.
3. Cinderhaze Wretch dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
4. Repeat.