Beifong's Bounty Hunters + Gravecrawler + Spawning Pit + Horizon Explorer

Beifong's Bounty Hunters

Gravecrawler

Spawning Pit

Horizon Explorer

How it works

1. Activate Spawning Pit 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 Spawning Pit ability.
4. Activate Spawning Pit by sacrificing the land.
5. When the land dies, Beifong's Bounty Hunters triggers, returning the land from your graveyard to the battlefield untapped due to Horizon Explorer.
6. Resolve the Spawning Pit ability.
7. Activate the land by tapping it, adding at least .
8. Cast Gravecrawler from your graveyard by paying .
9. Repeat.