This clever loop transforms graveyard fuel into an endless army by turning every single token creation step into a multi-token cascade. It all begins when Necrogenesis exiles a creature card from an opponent's graveyard to make a Saproling token; Chatterfang, Squirrel General immediately steps in with its replacement effect, doubling your yield by tossing in a bonus Squirrel token alongside it. You then feed both of those newly minted creatures to Phyrexian Altar to generate the exact mana needed to fund Void Attendant. Void Attendant's ability recycles that exiled card right back to its owner's graveyard while producing an Eldrazi Scion token—which Chatterfang, Squirrel General once again doubles by hitching a second Squirrel to the bargain. Sacrificing this fresh pair of tokens to Phyrexian Altar more than covers your costs, leaving you with net-positive mana and an endless chain of sacrifices, enter-the-battlefield triggers, and death events.