A well-geared Discipline priest who just keeps himself up? >.>
The elemental draenei shaman scattered throughout SMV are nice for leveling weapon skills, but I believe since they're immune to all attacks you won't be able to build combo points or rage. There's also the guys in Blasted Lands that take full damage from attacks but it doesn't actually kill them, though you'd be forced to attack from the front unless you get a friend to help you out.