Activate Spawning Pit's first ability by sacrificing Cauldron Familiar.
Activate Cauldron Familiar by sacrificing a Food, returning Cauldron Familiar to the battlefield from your graveyard.
Cauldron Familiar and Skeleton Crew trigger.
Resolve the Skeleton Crew trigger, creating a token and a Food token.
Resolve the Cauldron Familiar trigger, causing each opponent to lose 1 life and you to gain 1 life.
Repeat
This clever loop transforms your graveyard into an endless engine of life-drain and token generation by feeding Cauldron Familiar back and forth into Spawning Pit. Each time the cat leaves your graveyard, Skeleton Crew's static pump and trigger-crafting ability turns that departure into a brand new Skeleton Pirate token, which Peregrin Took happily upgrades by tacking on an extra Food token to every token creation event. You can then sacrifice those freshly minted Foods to feed Cauldron Familiar's return, draining your opponents out of the game while generating a massive army of creatures.