This clever loop leverages Xathrid Demon and its mandatory upkeep sacrifice trigger to feed upon your own resources, targeting Enduring Angel in its transformed Angelic Enforcer state. Because Angelic Enforcer's power dynamically scales directly with your life total, its sacrifice drains your opponents for that massive amount of life all at once. Meanwhile, Enduring Angel's replacement effect ensures that whenever your life total would be reduced to 0 or less—or whenever it is put into the graveyard from the battlefield—it simply transforms instead of dying for good, providing a resilient engine that continually resurrects to fuel the Demon's hunger.