Mikaeus, the Unhallowed + Goblin Bombardment + Wingrattle Scarecrow

Mikaeus, the Unhallowed

Goblin Bombardment

Wingrattle Scarecrow

How it works

1. Activate Goblin Bombardment by sacrificing Wingrattle Scarecrow.
2. When Wingrattle Scarecrow dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Resolve the Goblin Bombardment ability.
4. Activate Goblin Bombardment by sacrificing Wingrattle Scarecrow.
5. When Wingrattle Scarecrow dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. Resolve the Goblin Bombardment ability.
7. Repeat.