Note: Clicking a cell door will tell you what kind of key it requires.
Speak to Druzzil Ro at ( 45, -67, 13 ) Copy/waypoint 45, -67, 13
either tab to her and press h, or kill an enforcer (in one of the cells) for the Justicarium Key to her cell
Obtain a mithril cell key from a green shiny at ( 28, -67, 9 ) Copy/waypoint 27.95, -67.02, 8.59, then unlock the cell door at ( 21, -68, -5 ) Copy/waypoint 20.53, -67.51, -5.46
Kill Balgros at ( 22, -68, -26 ) Copy/waypoint 22.02, -67.60, -26.17 to obtain a feyiron cell key.
If you hug the east wall, you can get back to the corner and fight Balgros there without aggroing the enforcer.
Open the door to Tayil N'Velex's cell at ( 11, -67, -7 ) Copy/waypoint 11, -67, -7 and speak to her.
Kill the seven Vul adherents and Fathad Zastim on the beach to obtain the Shadow Gem (you have to kill them all to break the barrier regardless of when you get the Shadow Gem).
Go up the ramp at ( 30, 2, -32 ) Copy/waypoint 29.79, 2.41, -31.59. Click the big purple barrier at the top of the ramp to open the way forward.
Destroy the barrier blocking the tower door at ( 30, 40, -88 ) Copy/waypoint 30, 40, -88.
Kill the 4 savage grathok. Move the piles of goo they drop to the tower to destroy the stone barrier.
Kill the shadowmen and gather the Void Shard Key at ( 78, 46, -116 ) Copy/waypoint 78, 46, -116 or ( 68, 45, -110 ) Copy/waypoint 68, 45, -110. (A black shiney on the floor)
Click the barrier blocking the stairwell at ( 75, 67, -98 ) Copy/waypoint 75, 67, -98 to open the way.
