Mikaeus, the Unhallowed + Yahenni, Undying Partisan + Lingering Tormentor

Mikaeus, the Unhallowed

Yahenni, Undying Partisan

Lingering Tormentor

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. Resolve the Yahenni ability.
4. Activate Yahenni 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 Yahenni ability.
7. Repeat.