Activate Altar of Dementia twice by sacrificing another nontoken creature you control and Slimefoot and Squee.
When the creatures die, Pitiless Plunderer triggers four times, creating four Treasure artifact tokens.
Resolve the Altar of Dementia abilities, causing target player to mill cards equal to the sacrificed creatures' powers.
Activate the Treasures by tapping and sacrificing them, adding 1.
Activate Slimefoot and Squee by paying 1 and sacrificing a Saproling.
When the Saproling dies, Pitiless Plunderer triggers twice, creating two Treasure artifact tokens.
Resolve the Slimefoot and Squee ability, returning it and another creature from your graveyard to the battlefield.
When Slimefoot and Squee enter the battlefield, it triggers, creating a 1/1 Saproling creature token.
Repeat.
This self-sustaining loop relies on the death-trigger engine of Pitiless Plunderer and Teysa Karlov to constantly refund and multiply your resources. By sacrificing creatures to Altar of Dementia, you feed the Plunderer's greed while digging through your library, all while Teysa Karlov doubles up the resulting death triggers to ensure you generate a surplus of Treasure tokens. This torrential flow of mana and fodder lets you activate Slimefoot and Squee over and over again, resurrecting both themselves and a companion from the grave while spawning fresh Saproling tokens on arrival to keep the cycle spinning infinitely.