Yahenni, Undying Partisan + Lingering Tormentor + Hardened Academic

Yahenni, Undying Partisan

Lingering Tormentor

Hardened Academic

How it works

1. Activate Yahenni 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 Yahenni ability.
5. Repeat.

This elegant loop turns Lingering Tormentor into a perpetual sacrifice engine by exploiting the interaction between its persist ability and the +1/+1 counters provided by Hardened Academic. Whenever you sacrifice Lingering Tormentor to Yahenni, Undying Partisan, the creature returns to the battlefield with a -1/-1 counter, but Hardened Academic immediately counters this drawback by placing a +1/+1 counter on it as cards leave your graveyard. Because state-based actions cause +1/+1 and -1/+1 counters to annihilate each other, Lingering Tormentor enters its next death with a clean slate, allowing you to feed Yahenni indefinitely while generating infinite death triggers and sacrifice counts.