This clever loop turns a graveyard recursion engine into an endless cycle of sacrifices by cleverly manipulating identity. You start by using The Master, Formed Anew: Body Thief, which enters the battlefield as a copy of Driver of the Dead thanks to its unique exile-and-copy ability. From there, you sacrifice The Master to Yahenni, Undying Partisan's activated ability, which simultaneously grants Yahenni indestructible and triggers the underlying Driver of the Dead copy's death ability. That trigger reaches into your graveyard to pull The Master right back onto the battlefield—still holding its identity as a copy of Driver of the Dead—ready to be sacrificed to Yahenni all over again to keep the loop spinning infinitely.