There is currently an area in Netherstorm (see video for location) called Chapel Yard that houses Tormented Citizens and Tormented Souls. These mobs have up to 7,850 health and change forms once you enter combat with them.
You need to be able to one shot them or provide enough shatter damage to get them down almost instant; basically kill them before they can change forms. You need to start out of combat of course so they don't change forms too soon.
If you have done it right, they will die but come back with barely any health. As soon as they come back you can kill them with an instant spell or auto attack once more and loot again, repeat.
There is not currently any loot table for these mobs like it says on Wowhead.com other then the quest item. This means they took it out on purpose because they knew about this or it is a mistake for the current build. In any case it allowed me to get almost all my quest items off of one mob and these may yield XP. I have no way to test that but if it does, you could spam this for XP. You can also apply this to any other mobs in the game that change forms upon combat.
Video
[YT]http://www.youtube.com/watch?v=yjLJEuZJXfs[/YT]
EnjoyCode:http://www.youtube.com/watch?v=yjLJEuZJXfs