The ArcatrazIntroduced in The Burning Crusade
The mighty Tempest Keep was created by the enigmatic naaru: sentient beings of pure energy and the sworn enemies of the Burning Legion. In addition to serving as a base of operations for the naaru, the structure itself possesses the technology to teleport through alternate dimensions, traveling from one location to another in the blink of an eye.
With Outland serving as the strategic battlefront in the ongoing Burning Crusade, the naaru recently used Tempest Keep to reach the shattered land. However, when the naaru set out from their stronghold, Prince Kael'thas and his blood elves quickly raided the dimensional fortress and assumed control over its satellite structures. Now, guided by some unknown purpose, Kael'thas manipulates the keep's otherworldly technologies, using them to harness the chaotic energies of the Netherstorm itself.