Stalwart Successor + Altar of Dementia + Gravelgill Axeshark

Stalwart Successor

Altar of Dementia

Gravelgill Axeshark

How it works

1. Activate Altar of Dementia 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 Altar of Dementia ability.
5. Repeat.