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

Prerequisites

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

Steps

1. Activate Carrion Feeder by sacrificing Butcher Ghoul When Butcher Ghoul dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
2. Resolve the Carrion Feeder ability
3. Activate Carrion Feeder by sacrificing Butcher Ghoul When Butcher Ghoul dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
4. Butcher Ghoul enters and dies as a state-based action due to having 0 toughness
5. Its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
6. Resolve the Carrion Feeder ability from step 4
7. Repeat from step 4

Results

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