Chthonian Nightmare + Priest of Gix + Fumulus, the Infestation + Yahenni, Undying Partisan

Chthonian Nightmare

Priest of Gix

Fumulus, the Infestation

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Priest of Gix.
2. When Priest of Gix dies, Fumulus's first ability triggers, creating a 1/1 Insect creature token.
3. Resolve the Yahenni ability.
4. 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.
5. When Priest of Gix enters the battlefield, it triggers, adding .
6. Cast Chthonian Nightmare by paying 1.
7. When Chthonian Nightmare enters the battlefield, it triggers, causing you to get EEE.
8. Repeat.

This clever loop relies on Chthonian Nightmare to constantly recycle Priest of Gix from the graveyard while its initial energy and the black mana generated upon re-entry pay for casting and activating the enchantment over and over. As the Priest repeatedly hits the graveyard, Fumulus, the Infestation turns those sacrifices into flying Insect tokens, providing the disposable fodder needed to fund Chthonian Nightmare's energy cost. Meanwhile, Yahenni, Undying Partisan acts as a willing sacrifice outlet to kick off the cycle, effortlessly transforming your continuous loop into an overwhelming tide of triggers, infinite black mana, and a massive, growing vampire.