Rakdos, the Muscle + Priest of Gix + Haunted Crossroads + Umbral Collar Zealot + Semblance Anvil

Rakdos, the Muscle

Priest of Gix

Haunted Crossroads

Umbral Collar Zealot

Semblance Anvil

How it works

1. Activate Umbral Collar Zealot by sacrificing Priest of Gix.
2. When Priest of Gix dies, Rakdos triggers.
3. Holding priority, activate Haunted Crossroads by paying , putting Priest of Gix from your graveyard onto the top of your library.
4. Resolve the Rakdos trigger, causing you to exile the top three cards of your library with the ability to play them until your next end step.
5. Resolve the Umbral Collar Zealot ability from step 1.
6. Cast Priest of Gix from exile by paying 1.
7. When Priest of Gix enters the battlefield, it triggers, adding .
8. Repeat.

This loop relies on Semblance Anvil to massively discount creature spells, reducing the mana cost of Priest of Gix down to a single generic mana so that it can be recast profitably using the three black mana generated upon its entry. Umbral Collar Zealot provides the necessary sacrifice outlet, while Haunted Crossroads neatly loops the Priest right back to the top of your library in response to the stack. Meanwhile, Rakdos, the Muscle turns this endless cycle of sacrifices into fuel by exiling your entire library card by card, allowing you to eventually cast and win with any spell hidden within your deck.