If the second Kell Dragon is alive at the 8 minute mark of the fight, Power of the Master starts to do a lot more damage. That's what wiped us the first few times we tried HM Styrak.
We finally took him down last night, this mechanic must have been what was killing us. After whipping the DPS to bring up their numbers we got Styrak down so he only enraged around 6-7% and only lost a couple of raiders.
FWIW, we noticed that you pretty much have to have a sustained DPS throughout the whole fight so you can keep up with the enrage timer. For other guilds our 4 DPS were between 1.2 mil and a hair under a mil, the healers popped in 350k between them and the tanks picked up the rest. As we ended up having 2 sorcs energy issues were only of a concern when Styrak was in ghost form and the healers alternated DPS while the other healer re-charged. The other key was to make sure the ranged DPS who would suffer the most from moving (i.e. our Arsenal Merc and Sorc were able just to turret and not move to much)