Ghost Howl is a massive white worg and a respected beast among the tauren for his aid during the Third War. Though his exact contributions are vague, it can be assumed that Ghost Howl fought against the Burning Legion's army in an attempt to take Mulgore during the Legion's invasion and the Battle of Mount Hyjal.
During the Ghost Howl's battles he attained a savage wound from a particularly nasty demon. Despite Azeroth's victory, the wolf continues to carry the wound, the pain of an unhealable wound tormenting his spirit and causing him to grow hostile towards the tauren and their allies. He now spends his final days roaming Mulgore in solitude.
The aging hunter Skorn Whitecloud, resident of Bloodhoof Village, once encountered the mighty Ghost Howl in his youth and, though unsuccessful in his own attempts to end the wolf's suffering spirit, commends those adventurers able to slay and salvage his demon-scarred hide.
The key to finding Ghost Howl is mainly patience. He is an uncommon mob and won't always be where common sightings say he is. He has been spotted the most times around [39, 41], the ditch just off to the West of the main road before heading up into Thunder Bluff.
His roaming path also seems to span up and around the very North-West/North-East parts of the region, all within relative distance to Thunder Bluff.
In order to get the quest for killing Ghost Howl, you must kill him first and then right-click on the Demon Scarred Cloak to be prompted by the Quest text. You can also wear the item after you've handed it in by dragging it onto your Back item slot. Right-clicking does not work.
After you've completed the quest for Ghost Howl, Skorn Whitecloud he will now always say, "You killed Ghost Howl. You're a stud.", when spoken to.