This quest is not available in game.
Use Morbent's Bane on Morbent Fel, kill Morbent Fel, then return Morbent's Bane to Sven at his camp.
Morbent Fel hides in his lair, the house perched atop the hill to the east overlooking the Raven Hill cemetery. His time in this land is drawing to an end...
Use Morbent's Bane against him. It will render his protective magics powerless.
Slay him. Slay him, and save us from his wickedness. Be the instrument of my revenge, and a hero of Duskwood!