Wingrattle Scarecrow + Thran Vigil + Yahenni, Undying Partisan

Wingrattle Scarecrow

Thran Vigil

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Wingrattle Scarecrow.
2. When Wingrattle Scarecrow dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Thran Vigil triggers, putting a +1/+1 counter on Wingrattle Scarecrow.
4. Resolve the Yahenni ability.
5. Repeat.