Umbral Collar Zealot, Trapjaw Kelpie, and Thran Vigil

Prerequisites

• Umbral Collar Zealot on the battlefield
• Trapjaw Kelpie on the battlefield
• Thran Vigil on the battlefield

Steps

1. Activate Umbral Collar Zealot by sacrificing Trapjaw Kelpie
2. When Trapjaw Kelpie dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. Thran Vigil triggers, putting a +1/+1 counter on Trapjaw Kelpie
4. Resolve the Umbral Collar Zealot ability
5. Repeat

Results

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