This quest was marked obsolete by Blizzard and cannot be obtained or completed.
Find a way to summon and slay the Duke of Cynders, the Duke of Fathoms, the Duke of Zephyrs and the Duke of Shards and report back to Commander Mar'alith in Cenarion Hold. You must also bring Tactical Task Briefing V in order to complete this quest.
The links between the Twilight's Hammer and the Abyssal Council are proving to be more important than we had expected.
We believe the elemental nobles known as the Abyssal Dukes are one of the primary force organizing the Twilight's Hammer cultists. Find a way to lure the four Abyssal Dukes into our plane of existence and destroy them!
Your dedication and prowess in past assignments have led us to choose you for this particular assignment. We are certain you will succeed in this endeavor.