I'm a V3 Nightblade and have run into a bit of hitch on this fight. I can't kill her, and (unless I screw up) she can't really kill me either.
I figured out pretty quick that you have to kill the orbs, but they take me ~4 melee hits to actually kill them, more if I switch to ranged. If I'm lucky and manage to get one, it usually means I miss the other two and she heals. I've tried using Path of Darkness (my only AoE) but I may as well have just tossed feathers in the air for all the good it did.
I managed to get her down to ~60% health once (took me about an hour), but then I got distracted by the adds and missed the first orb, causing me to miss the other two, and then she was back at full health. I let out a very loud swear, and let myself die because I just didn't want to deal with it anymore.
I'm not really sure why I'm having so much trouble with this, and the only help I found was a video of a guy having the same problem with a DK at V4, so I'm assuming there's something else I'm missing if we're the only two having trouble. I don't think it's a spec/gear issue, and I think I'm probably an average player in terms of skill level (considering I made it this far with little trouble). I think the fight would be simple if I could one-shot the orbs, but it's not possible.
I'm hoping there's something obvious I'm missing and it's just a case of me being stupid. This fight is just sapping all my motivation to play.
Here's the video I mentioned above demonstrating the problem:
http://youtu.be/o41rxWP7VfA