Lesser Masticore + Thran Vigil + Yahenni, Undying Partisan

Lesser Masticore

Thran Vigil

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Lesser Masticore.
2. When Lesser Masticore 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 Lesser Masticore.
4. Resolve the Yahenni ability.
5. Repeat.