Mikaeus, the Unhallowed + Rendclaw Trow + Yahenni, Undying Partisan

Mikaeus, the Unhallowed

Rendclaw Trow

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Rendclaw Trow.
2. When Rendclaw Trow 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 Rendclaw Trow.
5. When Rendclaw Trow 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.