Mikaeus, the Unhallowed + Restless Apparition + Yahenni, Undying Partisan

Mikaeus, the Unhallowed

Restless Apparition

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Restless Apparition.
2. When Restless Apparition 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 Restless Apparition.
5. When Restless Apparition 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.