Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Phyrexian Altar, and Sightless Ghoul

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Phyrexian Altar on the battlefield
• Sightless Ghoul on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing Sightless Ghoul When Sightless Ghoul 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 Sightless Ghoul When Sightless Ghoul 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