Stalwart Successor + Goblin Bombardment + Grazing Kelpie

Stalwart Successor

Goblin Bombardment

Grazing Kelpie

How it works

1. Activate Goblin Bombardment by 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, Stalwart Successor triggers, putting a +1/+1 counter on Grazing Kelpie
4. Resolve the Goblin Bombardment ability.
5. Repeat.