At long last you've arrived at the place where the Screaming Mace is kept. Soaked in blood and armed with your Congealed Blood Sphere, there is but one final step to take before the mace will be yours!
When you zone in you will notice four idols in the center of the room. Clicking the correct one will spawn Gorfuzod the Keeper, while clicking any other one will spawn four harbingers of Fear. Examining Congealed Blood Sphere will highlight the proper idol. Once the Keeper is dead, pick up the mace hovering above the table in the back of the room.
This zone is listed under the name "The Inner Sanctum" in the Persistent Instances tab, even though the parent instance is the Sanctum of Fear. Also, even though there is a persistence for this instance, it cannot be reentered unless you're grouped with another player that has the required quest, the Screaming Mace.