This clever little loop relies on the neat interaction between a creature with persist and Ivy Lane Denizen, where the +1/+1 counter placed upon entry instantly cancels out the creature's -1/-1 counter when it returns from the graveyard. Viscera Seer provides the essential sacrifice outlet to send the creature away in the first place, allowing you to repeat the cycle as often as you like. By feeding the creature to Viscera Seer over and over, you not only filter your library with infinite scry triggers, but you also generate an endless stream of enters-the-battlefield and leaves-the-battlefield events.