Proceed through the rest of the zone and kill the Council of Four at ( 1340, 784, 39 ) Copy/waypoint 1340, 784, 39
Note that you cannot log out during this zone. If you do, the Stones of Thudos in the zone will respawn, preventing you from opening any door leading higher.
Use the Portal to Heart of Thudos that appears at ( 1501, 784, 42 ) Copy/waypoint 1501, 784, 42.
Click on The Thudos Corestone at ( -216, 113, 160 ) Copy/waypoint -216, 113, 160 to cleanse the The Thudos Corestone of the errant elemental aspects.