Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Geralf's Messenger, and Hammerhead, Maggia Boss

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Geralf's Messenger on the battlefield
• Hammerhead, Maggia Boss on the battlefield

Steps

1. Activate Hammerhead 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 Activate Hammerhead 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
3. When Geralf's Messenger enters, it triggers, causing an opponent to lose 2 life Resolve both Hammerhead abilities from step 1 and 4
4. Repeat

Results

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