The Yoke of Seeming was a Sith artifact that pre-dated the arrival of the Dark Jedi Exiles. XoXaan seized it for herself. It was said to be able to make one appear as anyone or anything, although it burned the flesh while doing it.
Much later, Haazen acquired it and installed it as one of his cybernetic parts. It significantly increased his connection to the Living Force and allowed him to cloud other Jedi's senses, hiding his true intentions from them. In addition to clouding his intentions, the Yoke transmitted to all Force-users the sense of himself that Haazen wished to convey. So while other Jedi could accurately see his true disfigured form, they would not react too viscerally to it. At his own preference, Haazen could also minimize its effects as he did during a discussion with Lucien Draay, during which he wanted to convey revulsion.
- Knights of the Old Republic 9: Flashpoint Interlude: Homecoming (First appearance)
- Star Wars: Knights of the Old Republic: Vindication (First identified as Yoke of Seeming)