Read the Tainted Memorandum and speak to Alamar Grimm inside Anvilmar above Coldridge Valley.
While you were helping me out, this memorandum was given to me to pass on to you. Take some time to read it when you have a chance. I'm thinkin' it came from the warlock trainer Alamar. Take a gander at it and go find him inside Anvilmar when you've a chance.
And watch yerself, [player], your kind ain't too trusted 'round these parts.