This quest is not available in game.
Bring Ambassador Malcin's Head to Bragor Bloodfist in the Undercity.
Malcin claims he is outside Razorfen Downs. This ambassador must be slain--his mission a failure in the eyes of the Lich King.
His presence there does explain much of what we've discovered about the area--some of the quilboar have grown frightfully powerful while showing signs of the Plague in their own way. Truly that must be a sign of some sort of deal they've struck.
Find Malcin and slay him, <name>. Return to me after the deed is done.