Guild Wars 2

So, I’ve been trying since the Gauntlet release to get the 8 orb ‘Light Up The Darkness’ achievement. I’ve been able to get 8 crystals tossed at her, but fail each time due to being dropped. I get her down to around 30-40% health.
Here is the build I’m running, including gear, food, and skill setup.
http://gw2skills.net/editor/?fYEQJAqYlUmiP3ey5E95EymCgqC5eYUOVT1pgriPA-jQxAYrAm8KiGbboIas6HMVJRUtMAVTA-e
I have 7 on Mouse Button 4 (Back Button),
6 on Mouse Button 5 (Forward Button),
and 8 on Mouse Button 3 (click on scroll wheel).
Any help would be absolutely wonderful!!!

multi task. You have to keep on attacking her while doing the 4th to 8th orbs. I was a super tanky character when I fought her and didn’t have problem downing her as long as I keep attacking her while doing the orbs.

Thank you Calmwinds, I was finally able to do it. The floor was literally dropping right as I did, but I still did it!