Stalwart Successor + Goblin Bombardment + Kithkin Spellduster

Stalwart Successor

Goblin Bombardment

Kithkin Spellduster

How it works

1. Activate Goblin Bombardment by sacrificing Kithkin Spellduster
2. When Kithkin Spellduster dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Kithkin Spellduster enters, Stalwart Successor triggers, putting a +1/+1 counter on Kithkin Spellduster
4. Resolve the Goblin Bombardment ability.
5. Repeat.