Stalwart Successor + Viscera Seer + Gravelgill Axeshark

Stalwart Successor

Viscera Seer

Gravelgill Axeshark

How it works

1. Activate Viscera Seer by sacrificing Gravelgill Axeshark
2. When Gravelgill Axeshark dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Gravelgill Axeshark enters, Stalwart Successor triggers, putting a +1/+1 counter on Gravelgill Axeshark
4. Resolve the Viscera Seer ability.
5. Repeat.