Even after everything that's happened, the world outside the Horde's walls is still a strange one to Adora. Each day she's learning more about her growing powers as She-Ra, including something new: the ability to heal corrupted runestones. Runestones are the magical source from which princesses like Frosta, Mermista, and Perfuma draw their power, but Glimmer knows of another runestone -- one with a dark past. Long ago a fire princess ruled the lands...