Grumgully, the Generous, and Hammerhead, Maggia Boss

Prerequisites

• Grumgully, the Generous on the battlefield
• Hammerhead, Maggia Boss on the battlefield

Steps

1. Activate Hammerhead by sacrificing the persist creature
2. When the persist creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it and at least one +1/+1 counter on it due to Grumgully
3. Remove a -1/-1 counter and a +1/+1 counter from that creature as a state-based action
4. Resolve the Hammerhead ability
5. Repeat

Results

• Infinite +1/+1 counters on a creature
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers