Fortify Archery by 70%, Fortify Destruction 50%, Unenchanted versions of the robes can be crafted at the Volkihar Shipyard blacksmith under 'misc'.
Any version of these robes can be worn by followers. The robes are also craftable under miscellaneous in at any forge. The robes (crafted in the realm of Molag Bal known as Coldharbour) are second to none for all classes. These highly enchanted robes help Molag's minions carry out his desires throughout the plane of Tamriel and beyond. The other two chests are on either side of the golden throne in the Throne Room of the Master Throne Wing.It is next to the desk in the back of the Temple of Molag Bal inside Valerica's Tower The robes can be found inside three chests in Castle Volkihar.
