Alright found this out awhile ago on beta, and I've been busy leveling my pally, but hope this still works (worked on live, might be patched though)
Almost everyone has seen the Fel Reaver running around in the outlands, and may or may not have killed or been killed by it, never the less, you can tell it packs a punch!
Well I'm here to teach you how to get the BEST pet in the game...the fel reaver.
First, you must be an eng. (low level is fine) and go to shimmering flats and buy the schematic for Gnomish Universal Remote
http://www.wowhead.com/?spell=9269#z0z
next create it and head on down to the outlands, if all works as planned, this should happen.