Chthonian Nightmare + Priest of Gix + Fumulus, the Infestation + Phyrexian Altar

Chthonian Nightmare

Priest of Gix

Fumulus, the Infestation

Phyrexian Altar

How it works

1. Activate Phyrexian Altar by sacrificing Priest of Gix, adding one mana of any color.
2. When Priest of Gix dies, Fumulus's first ability triggers, creating a 1/1 Insect creature token.
3. Activate Chthonian Nightmare by paying EEE, sacrificing the Insect and returning Chthonian Nightmare from the battlefield to your hand, returning Priest of Gix from your graveyard to the battlefield.
4. When Priest of Gix enters the battlefield, it triggers, adding .
5. Cast Chthonian Nightmare by paying 1.
6. When Chthonian Nightmare enters the battlefield, it triggers, causing you to get EEE.
7. Repeat.

This ingenious loop relies on a self-sustaining cycle of sacrifice and recursion fueled by Priest of Gix, which generates three black mana upon entering the battlefield to easily recast Chthonian Nightmare. Phyrexian Altar provides the initial sacrifice outlet to bin the Priest and yield additional mana of any color, while Chthonian Nightmare handles the energy investment needed to continually bounce itself and pull the Priest right back out of your graveyard. Meanwhile, Fumulus, the Infestation turns every sacrificed nontoken creature into a steady stream of flying Insect tokens, leveraging its first triggered ability to fuel the Nightmare's sacrifice cost and setting the stage for incremental life drain as your swarm grows.