Keritose Bloodblade at the Shadow Vault wants you to use an Eye of Dominion to take control of a captured Eidolon Watcher.
Seize Control of an Eidolon Watcher
Look what we have here... eyes of dominion. The Cult normally goes to great lengths to keep these things safe, but I suppose their options for retreat are few when we're slaughtering them in their own home.
The eyes allow a being of any relative power to control an undead minion's actions precisely. As you can imagine, this can be extremely useful when it comes to your typical clumsy ghoul or skeleton.
Care to try your hand at it? Use one of the eyes to control a captured shade.
Nothing to it, eh? Any intelligent being should have little trouble controlling lesser undead. I suspect only the likes of a true necromancer could use these to sieze control of any of the more powerful undead. That won't be a problem though - I can already think of quite a variety of destruction we can wreak with even the most paltry minions.