This clever loop transforms a planeswalker into an endless engine of discovery, fueled entirely by the overlapping synergies of the battlefield. By using Sarkhan, the Dragonspeaker's +1 ability to temporarily turn him into a creature, he becomes a valid target for Viscera Seer's sacrifice outlet. Because Sarkhan is a legendary creature when he hits the graveyard, Ratadrabik of Urborg steps in to trigger his replacement effect, spitting out a nonlegendary copy that retains all of Sarkhan's planeswalker and creature characteristics. You can then animate and sacrifice this new copy over and over again, letting Viscera Seer sift infinitely through your library while generating endless death and sacrifice triggers.