Beifong's Bounty Hunters + Gravecrawler + Tiller Engine + Yahenni, Undying Partisan

Beifong's Bounty Hunters

Gravecrawler

Tiller Engine

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Gravecrawler.
2. When Gravecrawler dies, Beifong's Bounty Hunters triggers, earthbending a land that can tap to produce at least .
3. Resolve the Yahenni ability.
4. Activate Yahenni by sacrificing the land.
5. When the land dies, Beifong's Bounty Hunters triggers, returning the land from your graveyard to the battlefield tapped.
6. When the land enters, Tiller Engine triggers, untapping the land.
7. Resolve the Yahenni ability.
8. Activate the land by tapping it, adding at least .
9. Cast Gravecrawler from your graveyard by paying .
10. Repeat.