Bargaining with Shadows

From the clues you've been able to piece together, it appears that Levia was looking to conduct a ritual in the libraries beneath Dalaran - most likely to summon this "Agatha" she has become so infatuated with. I'm afraid this is a little out of my area of expertise, so I'm going to have to call in a favor. I'll send for assistance from the Council of the Black Harvest. One of their warlocks will meet you in the Chamber of the Guardian to assist with your investigation. I hope we're not too late.