Stalwart Successor + Blasting Station + Grazing Kelpie

Stalwart Successor

Blasting Station

Grazing Kelpie

How it works

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