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

Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight

Phyrexian Altar

Sightless Ghoul

How it works

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

This engine is elegantly fueled by Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, which grants your other nontoken creatures persist on its back side while simultaneously giving creature spells convoke on its front face. By sacrificing Sightless Ghoul to Phyrexian Altar, you generate mana while triggering the Ghoul's native undying ability to return it with a +1/+1 counter. Once that counter is removed through subsequent sacrifice, the persistent effect granted by Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight steps in to bring Sightless Ghoul back with a -1/+1 neutralizing pair, allowing the cycle to repeat indefinitely.