Activate Selvala by paying and tapping it, adding at least 1.
Activate Yahenni 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 looping resurrection engine relies on Slimefoot and Squee acting as the ultimate recursive engine, using its activated ability to pull itself and Selvala, Heart of the Wilds straight back from the graveyard to the battlefield. To fund this costly recursion, Selvala taps for a massive influx of mana based on the high power provided passively to your board by Frostcliff Siege's Temur mode. Meanwhile, Yahenni, Undying Partisan puts those sacrifices to work by safely eating creatures when needed, while Slimefoot and Squee's own entry trigger continually replenishes the fodder by generating a fresh Saproling token every single iteration.