Yea this one has been very challenging for my guildmates. Eventually they figured it out. When I arrived there, I had an equally challening fight, but with their advice and some tweaking to my build (don't be afraid to mix it up) I did it after about 7 deaths. Here is what I did:

1. Just ignore the add. The add is frakking annoying, it keeps knocking you down or staggering you and throws AoE at you (depending if its ranged or melee), but once you kill it, another one respawns. So what I did was just CC the add with a long term stun. I used the 1h and shield power bash to do this. This left the add unable to do anything for 10 secs. Dragonknights also have petrify for this. CC the add every time it becomes active again.

2. Kill the Orbs with AoE. The key to this fight is killing the orbs in time so they don't heal the boss, but you in stead. I tried to do it by bursting them down 1 by 1. Didn't work. So what you do is you stand on top of the boss, and when the orbs are in range of your AoE, you use that AoE untill the orbs are dead (usually 2 hits).

3. Be sure to slot a heal/damage shield or some other potent defensive ability and use it when the add is becoming active again or when you get at low health.

4. Apart from using your AoE abilities on the orbs, try to save up resources for healing/shielding yourself and for doding/blocking. Do this by only using quick and power attacks on the boss or doing the occasional shield bash when you have enough stamina to spare (this does a lot of damage).

5. Final point. Whenever she pulls you in/uses a channel to stun you: Break out of it by using the left+right mouse button! This allows you to evade her attacks and more importantly, the attacks of the add if it is not cc'ed.

Using these tactics after thinking over the fight, made me complete the fight with succes in 1 go. It was close, but I was at lvl 40 in lvl 36 gear. I hope this will help you to clear the fight. Please post here if you succeed!