Stalwart Successor + Blasting Station + Gravelgill Axeshark

Stalwart Successor

Blasting Station

Gravelgill Axeshark

How it works

1. Activate Blasting Station by tapping it and 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, Blasting Station and Stalwart Successor trigger.
4. Resolve the Blasting Station trigger, untapping it
5. Resolve the Stalwart Successor trigger, putting a +1/+1 counter on Gravelgill Axeshark
6. Resolve the Blasting Station ability from step 1
7. Repeat.