Quest: Lost Keys - click on the runestone at -195, 0.19, 80 in Pharinich's room.
Go south through the gate that opened and follow the hallway to the next room ( -157, -24, 41 ) . This room is a series of raised platforms with the named in the center. Don't fall... it won't end well.
Quest: Lost Keys - click on the runestone at -10, 0.11, -203 in the Thoughtbleeder's room.
The gate to the west is now open. Follow the hallway to the next room. ( 103, 15, -137 )
Quest: Lost Keys - click on the runestone at 127, 16, -157
Speak to the haunted Amygdalan again. The gate to the west will open.
Go down the hallway and walk to the circle in the center of the final room.
Kill Baelon of Thule (96^^). During this fight Baelon will swing his mace at least once, dealing about 1.5 million damage to anyone in its path.
The trick is to run under his belly and stay there until he has almost no health. When he prepares to swing, you'll see a red area. Get out of it at highest priority. If you have any abilities that absorb killing blows, use them when you see the red glow.