In Kael Drakkel: Rogue
In Kael Drakkel, the King's Madness: Fjokar Frozenshard (click for map location image) spins random targets around so that their back faces him. Then, fairly often, he checks for players facing away from him; those who have their backs to him are susceptible to "Stab of Chaos". His PH is "a storm giant of nobility" at /loc -1741, 1460, -155, in the room south-east of King Tormax.
Location for your "kaelshard.txt" map file (note for all known Kael named spawn locations, see this quest entry):