Activate Viscera Seer by sacrificing another nonland creature you control.
When the creature dies, Beifong's Bounty Hunters triggers, earthbending a land.
Resolve the Viscera Seer ability.
Activate Viscera Seer by sacrificing the land.
When the land dies, Beifong's Bounty Hunters triggers, returning the land from your graveyard to the battlefield tapped.
When the land enters, Down in the Valley triggers, creating a creature token.
Resolve the Viscera Seer ability.
Repeat.
This vicious little loop relies on an endless cycle of sacrifice and resurrection to churn through your deck and flood the board. You begin by using Viscera Seer to sacrifice a creature, which triggers Beifong's Bounty Hunters to earthbend one of your lands into a resilient, ever-returning threat. Because that land is destined to come right back to the battlefield tapped whenever it dies or is exiled, you can immediately sacrifice the land-creature to Viscera Seer all over again. Every time that land re-enters the battlefield, it triggers Chapter II of Down in the Valley, generating a fresh 1/1 green Elf creature token that can then feed the Seer, keeping the engine running indefinitely.