Vault of the Hidden
Levels 38–48 · Premier · Qalia
Pillars leading into a temple like entrance in Tar Janashir. Cluttered with named mobs. 4 dots, 5 dots deeper in. Quest line seems likely, but not implemented yet.
Details
Source
Silky Venom wiki — http://www.whitetalon.com/dungeons/dungeonfinder.asp