Move to the center of the cage ( -84, -42, 161 ) Copy/waypoint -84, -42, 161 kill the level 74^ mob that spawns.
Note: This step should be completed ungrouped, with any assistance at max range from you, otherwise the quest won't update. If you are a pet class, then YOU must strike the death blow, not your pet.
Return to and speak to a senior Clay shackle monk at Tabernacle of Pain ( -30, -50, 166 ) Copy/waypoint -30, -50, 166 to complete the quest.