Stealthed. Smaller than Coldmist Widows. There are usually 2 or more with any Coldmist Widow in the Servants' Quarters of Karazhan. There might be one Coldmist Stalker patrolling solo in that area. Trap or sheep the stalkers while you burn down the widow. Since they are stealthed you want a hunter to throw a flare to make them visible and mark them for crowd control. If you can not make them visible before the fight have a rogue or prowling cat-druid get close enough to detect and mark them so that CC can pick up their target once the fight begins and they break stealth.