Yarus, Roar of the Old Gods + Cryptolith Rite + Obscuring Aether + Phyrexian Altar

Yarus, Roar of the Old Gods

Cryptolith Rite

Obscuring Aether

Phyrexian Altar

How it works

1. Activate Obscuring Aether by paying 1, turning it face-down as a 2/2 creature.
2. Activate Obscuring Aether by tapping it, adding .
3. Activate Phyrexian Altar by sacrificing Obscuring Aether, adding 1.
4. When Obscuring Aether dies, Yarus' second ability triggers, returning it from your graveyard to the battlefield face-down, then turning it face-up.
5. Repeat.

This clever loop transforms Obscuring Aether into a self-sustaining sacrifice engine by taking advantage of its unique ability to morph into a creature and back. When you tap the enchantment for mana using Cryptolith Rite, you can then sacrifice it to Phyrexian Altar to generate the mana needed to reset the cycle. Because the sacrifice sends it to the graveyard, Yarus, Roar of the Old Gods immediately catches the trigger to return it to the battlefield face down and turn it face up once more, seamlessly replacing the sacrificed permanent and fueling an infinite stream of sacrifice and entry triggers.