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 intricate recursion loop transforms Selvala, Heart of the Wilds into a massive mana engine, utilizing her ability to generate the exact resources needed to fund the graveyard-returning activation of Slimefoot and Squee. To keep the cycle spinning, Umbral Collar Zealot provides the necessary sacrifice outlet to bin the key legends, while the Saproling token created by Slimefoot and Squee upon reentry supplies the fodder to pay for their resurrection. Meanwhile, Maelstrom Wanderer grants haste to ensure your returning creatures are immediately ready to tap for mana or fuel further sacrifices without waiting.