There is an Engineering quest called "Aww Scrap!" that will send you down into the Dalaran Sewers to deliver a shipment of guns. Please Note:
>> MOST OF THE SEWERS IS A FFA PVP ZONE!<<
So to complete this quest without dying over and over its important to take the right entrance into the Sewers. The correct entrance is the one sandwiched between Krasus Landing & the Hunter Shop. Follow the stairs down, and you'll find yourself in a small space protected by guards. Your contact will be there.
While you are there, pick up the Fel Reaver Husk on the floor next to him and take it back to the Engineering shop. You'll get another Engineering related quest for it.