Activate Warren Soultrader by paying 1 life and sacrificing the persist creature.
When the persist creature dies, its persist ability triggers, returning the persist creature from your graveyard to the battlefield with a -1/-1 counter on it.
When the persist creature enters, Case of the Uneaten Feast triggers, causing you to gain 1 life.
Resolve the Warren Soultrader ability, creating a Treasure token.
When the Treasure enters, Mm'menon triggers, putting a +1/+1 counter on the persist creature.
Repeat.
This vicious loop turns a humble persist creature into an endless engine of sacrifice and resurrection, entirely fueled by Warren Soultrader's ability to turn life and fodder into Treasure. As each Treasure enters the battlefield, Mm'menon, Uthros Exile notices the artifact and hands out a +1/+1 counter that neatly neutralizes the -1/-1 counter left behind by the creature's persist resurrection. Meanwhile, Case of the Uneaten Feast quietly pads your life total with every creature entry—keeping you comfortably in the black to pay Warren Soultrader's life cost infinitely while pushing the Case ever closer to its solved state.