Umbral Collar Zealot + Lesser Masticore + Hardened Academic

Umbral Collar Zealot

Lesser Masticore

Hardened Academic

How it works

1. Activate Umbral Collar Zealot 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. Hardened Academic triggers, putting a +1/+1 counter on Lesser Masticore.
4. Resolve the Umbral Collar Zealot ability.
5. Repeat.