Activate Selvala by paying and tapping it, adding at least 1.
Activate Umbral Collar Zealot twice by sacrificing Selvala and Slimefoot and Squee.
Activate Slimefoot and Squee by paying 1 and sacrificing a Saproling, returning it and Selvala from your graveyard to the battlefield.
When Slimefoot and Squee enters the battlefield, it triggers, creating a 1/1 Saproling creature token.
Repeat.
This elegant loop revolves around recycling legendary threats to endlessly fuel Selvala, Heart of the Wilds' mana production, with Fires of Yavimaya granting crucial haste so your resurrected creatures can tap immediately. By feeding cards into Umbral Collar Zealot's sacrifice outlet, you continuously load your graveyard while filtering your draws. Finally, Slimefoot and Squee acts as the ultimate engine, using that generated mana and newly spawned Saproling tokens to bring everyone right back to the battlefield to do it all over again.