This clever loop relies on Mikaeus, the Unhallowed to grant undying to Grim Poppet, ensuring that every time the Poppet dies, it returns to the battlefield with a +1/+1 counter. Meanwhile, Bartolomé del Presidio provides a reliable sacrifice outlet that simultaneously pumps its own stats with +1/+1 counters. Because Grim Poppet enters the battlefield with three -1/-1 counters, those counters immediately annihilate the +1/+1 counter placed by undying through state-based actions, leaving the Poppet perpetually fresh and ready to be sacrificed to Bartolomé del Presidio all over again.