So your raid force is trying to take out King Zalak, and is failing after he's been "beefed up"? I bet it's due to those nasty Patriarchs that come to his aid.
Since the instance has been changed, when the Patriarchs reach King Zalak, they heal him (for A LOT), and also explode for a zone-wide AOE for 1500+ damage.
So, here's an easy way to beat those Patriarchs! To pull this off, you will need 3 'non-valuable' raid members (not a main tank, healer, or power battery). These members will need a ranged pull, such as a bow or a spell. They will be Suicide Helpers, so they cannot mind some debt. You raid force WILL get some debt as well, but IMHO, it's worth it!
After engaging the King, 3 Patriarchs spawn and run towards the King. 3 more spawn every 1.5mins or so.
While your main raid force is taking on Zalak and his cohorts, have your 3 Suicide Helpers remove all armor to avoid repair costs and to quicken their death.
When the patriarchs spawn (they come from different huts around the zone), have each of your 3 Suicide Helpers aggro 1 each, and let the Helpers die.
After the Helper dies, the Patriarch is reset (to non-aggro), and runs wanders around the zone, and does not help Zalak.
At this point, your helper should revive
in the zone, and return, ready for the next patriarch.
Rinse and repeat until you've beaten Zalak!
I have no idea how long this has been in effect, and no idea if/when they will change this, so if you can get your guild or raiding partners into this raid, use this asap
For those that don't know, King Zalak is a Group x4 instanced zone that you enter from the Commonlands in Zarvonn's Tower.