Stalwart Successor + Blasting Station + Trapjaw Kelpie

Stalwart Successor

Blasting Station

Trapjaw Kelpie

How it works

1. Activate Blasting Station by tapping it and sacrificing Trapjaw Kelpie
2. When Trapjaw Kelpie dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Trapjaw Kelpie 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 Trapjaw Kelpie
6. Resolve the Blasting Station ability from step 1
7. Repeat.