Mikaeus, the Unhallowed, Goblin Bombardment, and Grazing Kelpie

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Goblin Bombardment on the battlefield
• Grazing Kelpie on the battlefield

Steps

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. Resolve the Goblin Bombardment ability
4. Activate Goblin Bombardment by sacrificing Grazing Kelpie
5. When Grazing Kelpie 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

Results

• Infinite ETB
• Infinite LTB
• Infinite damage
• Infinite death triggers
• Infinite sacrifice triggers