Bhaal, Lord of Murder + Crystalline Crawler + Gravecrawler + Yahenni, Undying Partisan

Bhaal, Lord of Murder

Crystalline Crawler

Gravecrawler

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Gravecrawler.
2. When Gravecrawler dies, Bhaal triggers, putting a +1/+1 counter on Crystalline Crawler.
3. Resolve the Yahenni ability, giving it indestructible until end of turn.
4. Activate Crystalline Crawler's first ability by removing a +1/+1 counter from it, adding .
5. Cast Gravecrawler from your graveyard by paying .
6. Repeat.

This loop turns a modest graveyard crawler into an engine of endless sacrifices, fueled perfectly by the mana-generating flexibility of Crystalline Crawler. You use Yahenni, Undying Partisan to repeatedly sacrifice Gravecrawler, whose self-recursion lets it cast straight from the graveyard as long as you have the black mana and a Zombie in play (which Gravecrawler itself provides). Meanwhile, Bhaal, Lord of Murder watches every sacrifice happen, turning each death into a +1/+1 counter that refills Crystalline Crawler's battery so it can pay for the next casting of the spell.