I ran into a holy pally yesterday while farming on my 80 resto druid. It jacked my node, and for lols I attacked it. We went back and forth for about 20 mins until he went oom...and I popped tree and killed him. I find it funny that because how combat ratings and regen changed from 80-85. So because his heals hot for about the same as mine and cost about 4x as much, it makes it so that given enough time I can kill them because I still have unlimited mana....providing I don't get 1 shotted.
It is silly fun, give it a try.