I just ran into Rage Fire Chasm and gathered up 10 mobs, turned my back to them and waited until I was low health(unless you can heal). Run out of instance and rinse/repeat. It goes up pretty fast.

edit: I'd also like to point out that defense is very important for pve. If your clones are at 1 def and they take a single hit from a boss, it's gonna be a crushing blow for sure.