Umbral Collar Zealot + Lingering Tormentor + Hardened Academic

Umbral Collar Zealot

Lingering Tormentor

Hardened Academic

How it works

1. Activate Umbral Collar Zealot 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. Hardened Academic triggers, putting a +1/+1 counter on Lingering Tormentor.
4. Resolve the Umbral Collar Zealot ability.
5. Repeat.

This clever loop relies on the interaction between Umbral Collar Zealot's sacrifice outlet and Lingering Tormentor's persist ability, which constantly cycles the Tormentor back and forth between the battlefield and the graveyard. Whenever Lingering Tormentor leaves the graveyard to return via persist, Hardened Academic’s triggered ability notices cards leaving the graveyard and places a +1/+1 counter on the Tormentor. Because the Tormentor enters with a -1/-1 counter from persist, state-based actions immediately cause that -1/-1 counter and the new +1/+1 counter to annihilate each other, leaving the creature completely clean of counters and ready to be sacrificed to Umbral Collar Zealot all over again.