The sorceress Nimueh frequently performed her most powerful forms of magic (like hydromancy) within the confines of a cave. She animated a piece of clay shaped to resemble an Afanc and delivered it into Camelot's water supply from this cavern, as well as monitoring the aftermath of her various machinations from a stone scrying fount in the cave (The Mark of Nimueh). The High Priestess also prepared in this cave a poisoned goblet with Mortaeus flowers (The Poisoned Chalice).