The Bone Witch's Amulet

This item is provided for the quest.

Within the Halls of the Ancestors lay Slumbering Mjordin. One of them is Iskalder. (Typically, one with armor and spikes, although not all of the ones with spikes are Iskalder.)

Wake him, then use the amulet. You then must return to The Bone Witch, Iskalder in tow.