Stalwart Successor, and Hammerhead, Maggia Boss

Prerequisites

• Stalwart Successor on the battlefield
• Hammerhead, Maggia Boss on the battlefield

Steps

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

Results

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