The Mark of the Nexus-King

What I must now know is what the Ethereum have held inside the Mana-Tombs of Auchindoun. In your battles against the beasts of the stasis chambers of Bash'ir you may run across an item known as the Mark of the Nexus-King. Should you find such an item, return it to me immediately! It is the final piece in crafting a key that will allow access to the stasis chamber inside the Mana-Tombs.