The heroes have reclaimed the city of Drezen and the lost sacred banner known as the Sword of Valor, and in doing so have established a significant foothold behind enemy lines. With the demon armies still concentrating their attacks to the south, the heroes must now set off into the heart of the Worldwound to seek out powerful new allies and strike a mortal blow against the Templars of the Ivory Labyrinth! Demon's Heresy is a Pathfinder Roleplaying Game adventure for 9th-level characters who have gained three mythic tiers. The adventure utilizes rules from Mythic Adventures to portray a campaign of truly epic potential. An exploration of the eerie powers of the beings known as the worms that walk and an examination of the druidic beliefs of the Green Faith round out this volume. A bestiary of several monsters (including the third of six demon lords that will be presented during the campaign!) and part three of Robin D. Laws's new Pathfinder Journal also await discovery in this new installment of Pathfinder Adventure Path.