Confirming Ainurr. Everyone else is phased differently. For them Ravenholdt just has a bunch of NPCs in it (poison vendor, junkbox turnin guy). The can neither see you nor any of the legendary questline NPCs like Wrathion, etc. In fact, you can't even group summon into the area while it is phased, you have to fly a bit outside of it before the summon will work.