After Intentions of War you are sent back to the Throne Room (the Hall of Legends map) to activate a Kromzek teleporter (on the left side of the room). When entering the main room you can invis to the left and there stands the Kromzek Teleporter ( -301, -20, 1352 ) /waypoint -301.26, -20.47, 1352.40
Once you have activated the teleportal, take the teleporter and it will lead you to the next missing Ragebourne Officer Gavin Campbell ( -366, 159, -1891 ) /waypoint -366.16, 159.19, -1890.76 (hidden behind the pillars). The agent you speak with will tell you that he cant go on in the mission, and of course you volunteer to complete it, which means you are going to fight your way to the location of the door and open it.
Gavin Campbell has asked that I fight my way towards the entrance of the Temple of Rallos Zek and unlock the doors from within.
Go down on the large round elevator platform just North of Gavin. Then exit the room to the circular hallway and head around/down/south, clearing your way to and across the Arch of Zek. Unlock the gates at ( -612, 78, -1093 ) /waypoint -612, 78, -1093, then get back to Caerwyn Thomlin at the Ragebourne Outpost