A shaman makes that fight so much easier. For anyone with shamans I would suggest using wind shear on paletress during the nightmare phase. It decreases her dps and stops her from getting off 100% of her heals. Also, make sure you purge the renew she puts on the mob.
I set paletress as my shamans target then use a simple /stopcasting /cast wind shear macro to stop her from casting. My purge macro has focustarget so when I see the renw I press purge. I recommend a /stopcasting on that too.
