Shade is one of the three Aspects of Rhisis. She, like Iblis and Bubble, was created when Rhisis drew energies from three aspects of herself. Shade, who bears the official title of "Goddess of Fear and Rage" represents Shadow and Desires and is most commonly associated with Darkon. She created the Masquerpets and used them to kill the Humans and the Dwarpets. She started and fought the Heroes in the Hero and/or Clockworks wars.
Shade herself does not exist ingame, but models, textures and animations exist for her, so GMs can choose to appear as her if they want to.