Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Ashnod's Altar + Howlgeist

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

Ashnod's Altar

Howlgeist

How it works

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

This engine relies on the incredible synergy between Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight's back face granting persist to your nontoken creatures and Howlgeist's native undying ability. By sacrificing Howlgeist to Ashnod's Altar, you generate colorless mana while exploiting the interaction between its +1/+1 and -1/+1 counters: when it dies with a +1/+1 counter, undying brings it back, and when it dies with a -1/-1 counter from Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, its persist ability triggers to return it with a +1/+1 counter instead. This alternating cycle of counters allows Howlgeist to bounce endlessly between the battlefield and the graveyard, fueling the altar for infinite sacrifices and mana.