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 loop turns the graveyard into a revolving door by cycling Selvala, Heart of the Wilds and Slimefoot and Squee back and forth using their combined abilities and mana. Tyvar, Jubilant Brawler makes sure the setup stays smooth, while Umbral Collar Zealot provides the crucial sacrifice outlets to send your key pieces straight to the graveyard so Slimefoot and Squee can pull them right back out. Each iteration generates a fresh Saproling token and excess mana from Selvala's massive power, fueling an endless chain of sacrifices, enter-the-battlefield triggers, and surveils to sculpt your victory.