Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Geralf's Messenger, and Carrion Feeder

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Geralf's Messenger on the battlefield
• Carrion Feeder on the battlefield

Steps

1. Activate Carrion Feeder by sacrificing Geralf's Messenger When Geralf's Messenger dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
2. When Geralf's Messenger enters, it triggers, causing an opponent to lose 2 life
3. Activate Carrion Feeder by sacrificing Geralf's Messenger When Geralf's Messenger dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
4. When Geralf's Messenger enters, it triggers, causing an opponent to lose 2 life
5. Resolve both Carrion Feeder abilities from step 1 and 4
6. Repeat

Results

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