Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Umbral Collar Zealot, and Arcbound Prototype

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Umbral Collar Zealot on the battlefield
• Arcbound Prototype on the battlefield

Steps

1. Activate Umbral Collar Zealot by sacrificing Arcbound Prototype
2. When Arcbound Prototype dies, its modular ability and persist ability trigger
3. Resolve the modular trigger, putting Arcbound Prototype's +1/+1 counters on another artifact creature
4. Resolve the persist trigger, returning Arcbound Prototype from your graveyard to the battlefield
5. It will not have a -1/-1 counter on it due to its modular ability
6. Resolve the Umbral Collar Zealot ability
7. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite +1/+1 counters on artifact creatures you control
• Infinite surveil 1