Following some dialog he sends you to interrogate the captive Queen Lenya Thex.
Hail Queen Lenya Thex in the gardens below ( -75, 66, -554 ) Copy/waypoint -75, 66, -554.
Hail The Palace Overseer next to the Queen ( -77, 66, -553 ) Copy/waypoint -77, 66, -553.
He will give you a small amount of information to report.
Tell your master this, the seat of power is the valve that shall release the knowledge of the ancient one. This will be enough to keep him occupied. Now leave!
He gives a clue as to how to further the quest and obtain the fabled reward.
Unfortunately, your skills are not as grand as I was led to believe. However, you can redeem yourself. When my expedition is complete here, infiltrate this throne. Seek and destroy the one that keeps me from the key I seek. He has not made his presence known, but I can sense him cowering in the shadows of my overpowering radiance. Perhaps he will let himself be known when I am gone.