Rakdos, the Muscle + Priest of Gix + Haunted Crossroads + Cloud Key + Carrion Feeder

Rakdos, the Muscle

Priest of Gix

Haunted Crossroads

Cloud Key

Carrion Feeder

How it works

1. Activate Carrion Feeder 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 Carrion Feeder ability from step 1, putting a +1/+1 counter on it.
6. Cast Priest of Gix from exile by paying 2.
7. When Priest of Gix enters the battlefield, it triggers, adding .
8. Repeat.

This elegant engine relies on Cloud Key naming "creature" to reduce Priest of Gix's mana value from three down to two, meaning the black mana generated upon its entry completely refunds its casting cost with mana left over. By sacrificing the Priest to Carrion Feeder, you fuel Haunted Crossroads to instantly stack the Priest back onto your library just in time for Rakdos, the Muscle to exile it with permission to cast it from exile. As this loop repeats, Rakdos continually claws through your deck while Carrion Feeder grows infinitely large on a mountain of recurring sacrifices.