Mikaeus, the Unhallowed + Altar of Dementia + Lingering Tormentor

Mikaeus, the Unhallowed

Altar of Dementia

Lingering Tormentor

How it works

1. Activate Altar of Dementia by sacrificing Lingering Tormentor.
2. When Lingering Tormentor dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Resolve the Altar of Dementia ability.
4. Activate Altar of Dementia by sacrificing Lingering Tormentor.
5. When Lingering Tormentor dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. Resolve the Altar of Dementia ability.
7. Repeat.

This clever loop exploits a fascinating rules interaction between two opposing counter mechanics to fuel Altar of Dementia for an infinite mill victory. Lingering Tormentor naturally enters the graveyard and returns thanks to its native persist ability, coming back with a -1/-1 counter. However, Mikaeus, the Unhallowed generously grants the creature undying as well, meaning when that same Lingering Tormentor hits the graveyard a second time, the +1/+1 counter from undying will annihilate the existing -1/-1 counter via state-based actions, resetting its counterless state entirely. Because the persist and undying triggers alternate endlessly with each sacrifice, you can repeat this cycle indefinitely to grind away your opponents' entire libraries.