Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, and Carrion Feeder

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Carrion Feeder on the battlefield

Steps

1. Activate Carrion Feeder by sacrificing the undying creature
2. When the creature dies, its undying ability triggers, returning the creature from your graveyard to the battlefield with a +1/+1 counter on it
3. Activate Carrion Feeder by sacrificing the undying creature
4. When the creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
5. Resolve the Carrion Feeder abilities from step 1 and 3
6. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite +1/+1 counters on Carrion Feeder