I just did this quest today i was lvl 31, with qyzen. I play a telekenetic jc. i made sure to bubble qyzen and keep him bubbled, not only that but i let him do his thing while i healed and used all 3 interrupts.
while i couldnt stop 1/4 of her cast i was able to stop enough that qyzen didnt take as much damage as he would have, had i not interrupted anything.
i love the dps i do but the fact that she was doing so much damage, i had to suck it up and heal like there was no tomorrow. she actually died before i realized it, i got so into keeping qyzens health up so much that was stilling casting heals while he was standing next to me.