Mikaeus, the Unhallowed + Deathbringer Thoctar + Altar of Dementia

Mikaeus, the Unhallowed

Deathbringer Thoctar

Altar of Dementia

How it works

1. Activate Deathbringer Thoctar by removing a +1/+1 counter from it, dealing 1 damage to any target.
2. Repeat step 1 until Deathbringer Thoctar has no +1/+1 counters on it.
3. Activate Altar of Dementia by sacrificing Deathbringer Thoctar.
4. Deathbringer Thoctar dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
5. Resolve the Altar of Dementia ability, causing target player to mill cards equal to Deathbringer Thoctar's power.
6. Repeat.