Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Phyrexian Altar, and Vengeful Vampire

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Phyrexian Altar on the battlefield
• Vengeful Vampire on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing Vengeful Vampire When Vengeful Vampire dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
2. Activate Phyrexian Altar by sacrificing Vengeful Vampire When Vengeful Vampire dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. Repeat

Results

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