Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Phyrexian Altar, and Geralf's Messenger

Prerequisites

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

Steps

1. Activate Phyrexian Altar 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 Phyrexian Altar 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. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite colored mana
• Infinite death triggers
• Infinite lifeloss
• Infinite sacrifice triggers