Activate Shilgengar twice by sacrificing Gruff Triplets and Slimefoot and Squee.
When Slimefoot and Squee and Gruff Triplets die, Pitiless Plunderer triggers twice and Gruff Triplets' second ability triggers once.
Resolve the Pitiless Plunderer triggers, creating two Treasure artifact tokens.
Resolve the Gruff Triplets trigger, putting a number of +1/+1 counters equal to Gruff Triplets' power on each creature you control named Gruff Triplets.
Resolve the Shilgengar abilities
Activate two Treasures by tapping and sacrificing them, adding two in any combination of , or .
Activate Slimefoot and Squee by paying 1 and sacrificing a Saproling.
When the creature dies, Pitiless Plunderer triggers, creating a Treasure artifact token.
Resolve the Slimefoot and Squee ability, returning it and Gruff Triplets from your graveyard to the battlefield.
Slimefoot and Squue and Gruff Triplets' second ability triggers.
Resolve the Slimefoot and Squee trigger, creating a 1/1 Saproling creature token.
Resolve the Gruff Triplets trigger, creating two token copes of it.
Activate Shilgengar by sacrificing a Gruff Triplets token.
When the Gruff Triplets token dies, Pitiless Plunderer triggers, creating a Treasure artifact token.
Resolve the Shilgengar ability
Activate two Treasures by tapping and sacrificing them, adding 1.
Repeat.
This self-sustaining loop relies on Shilgengar, Sire of Famine and Slimefoot and Squee to repeatedly cycle your graveyard while Pitiless Plunderer converts your casualties into the mana needed to keep the engine running. Every time creatures hit the dirt, Pitiless Plunderer generates the necessary Treasure tokens to fund your board, while Gruff Triplets constantly replenishes your sacrifice fodder by flooding the battlefield with token copies upon entry and accumulating massive +1/+1 counters when it perishes. By orchestrating these sacrifices through Shilgengar, Sire of Famine and Slimefoot and Squee's resurrection abilities, you effortlessly churn out endless death triggers, mana, and tokens.