This clever loop begins with Bartolomé del Presidio, who happily consumes Master of the Veil for a +1/+1 counter and sends the morph creature to the graveyard. That sacrifice immediately awakens Yarus, Roar of the Old Gods, whose second ability catches the dying Master of the Veil and sneaks it right back onto the battlefield face down before instantly flipping it face up. This resurrection triggers Master of the Veil's own ability, targeting itself to turn back face down so the whole cycle can start anew. Best of all, Yarus, Roar of the Old Gods also grants haste to keep your battlefield fluid, turning this self-sustaining engine into an endless loop of sacrifices and triggers.