Originally Posted by
Kintaii
The thing is, after she tosses up her huge reflect shield you're not really supposed to attack her at all. It's a cinematic thing; You get her to low health, she becomes invincible, spouts some crap in vicinity, and then despawns and spawns the Omega Turret as your final boss for the questline.
Or, well, that's how it's supposed to work. ;P
I've been talking with Genele lately about taking a look at the mechanics for The Informant part of the Constad questline and we've got some good ideas on how to get it a little more... stable. Hopefully after the Daily Missions/Collector update is out for Live, she and I can sit down and work on ensuring the questline does what it's supposed to do. ;)