Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Phyrexian Altar + Nardole, Resourceful Cyborg

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

Phyrexian Altar

Nardole, Resourceful Cyborg

How it works

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

This brilliant loop centers around Nardole, Resourceful Cyborg toggling back and forth between life and death, constantly fueling Phyrexian Altar for infinite mana and sacrifice triggers. While the Altar provides the graveyard conduit, the real engine is powered by the back face of Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight; as Isilu, Carrier of Twilight grants Nardole persist, it elegantly alternates with Nardole's native undying ability to reset its counters every time it dies. Though the front face of Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight and the extra mana from Nardole, Resourceful Cyborg's tap ability aren't strictly required for the core sacrifice loop, they sit ready to leverage the resulting creature spells, death triggers, and mana to overwhelm the table.