Stalwart Successor, Umbral Collar Zealot, and Heartmender

Prerequisites

• Stalwart Successor on the battlefield
• Umbral Collar Zealot on the battlefield
• Heartmender on the battlefield

Steps

1. Activate Umbral Collar Zealot by sacrificing Heartmender When Heartmender dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
2. When Heartmender enters, Stalwart Successor triggers, putting a +1/+1 counter on Heartmender Resolve the Umbral Collar Zealot ability
3. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers
• Infinite surveil