In order to complete this quest you will have to obtain the Spectral Bane from a box sitting on the floor next to Davian Crow. With the Bane in tow simply complete the second boss event in the dungeon, the Three Kings. There will now be an active Spectral Trap on the floor where you fought the Kings. On each side of this great hall you will find Spectral Screamers. Target them and use the Spectral Bane and lead them onto the Spectral Trap. Have your group do this to ten of the Screamers and you will receive completion credit for the quest.