The Howling Beast armor is the ultimate transmog for hunters who like the “wear what you kill” style of armor. I’m going to tell you up front that you need to get a gold medal in all 9 of the Mists of Pandaria challenge mode dungeons in order to earn it. If you’ve been thinking about getting this set, you will have to do so before the 6.0 patch drops and it is removed from the game. My guess is that means you have until about July-August, but that’s just a wild guess. It may seem insurmountable, but it’s definitely not. I previously wrote a couple of challenge mode guides at WoW Insider you may be interested in — Hunter specific, and a general getting started guide. In short, gear is not the barrier. Practice and finding a good team is. Check out OpenRaid if you don’t have any friends interested.
A unique feature of the challenge mode armor sets is they all have visual effects that activate when you attack. In the case of Howling Beast, this manifests as flames coming out of the shoulders and a laser sight coming out of the helm.