Even with the Kyuss' instaheal ability, it was really the Disjunction that pushed everything over the edge. If anything was egregious, it was that. The Disjunction in round 2 effectively took out 3 players at the beginning of the fight (and really ended up being the death of Grubber and Mak by removing their AC and save buffs) by the debuffing of about 20 spells coupled with the fact that Kyuss' will save DC to keep magic items was 35. If he had not been allowed access to that we could have collectively done the requisite 660 damage in 1 round, insta-heal or not.
If it makes our readers feel any better, the following was changed (to the best of my knowledge...I don't know if there is more) to make the fight more difficult, in no particular order:
* Removing despair would not lower Kyuss' Divine Rank to 0, which allowed him to cast his divine spells spontaneously (otherwise, he wouldn't have had access to 30 'Heals').
* Destroying the Vortex had no effect on Kyuss' AC/to hit/etc for the first fight session.
* Kyuss' was not forced to spend the first 1 or 2 rounds of combat crawling out of the obelisk.
* Each of the Brood Fiends was given a Rod of Cancellation to destroy the Sphere of Annihilation.
* Kyuss lost a spell that was worthless against us (Energy Drain) which was replaced with the most powerful spell possible against us (Disjunction)
* Kyuss lost a worthless feat for combat (Craft Arms and Armor) in exchange for a powerful epic-level feat (Improved Metamagic), which effectively gave Kyuss the ability to cast many more empowered Time Stops.
All that, and we still annihilated all of his allies (and there were a TON of them) are were almost able to kill him. JD is right...if Kyuss' had been played unchanged then the fight would have been easy. I would not go so far as to have called it anticlimatic, but the League would have won, hands down, no problem, Kyuss is punked. If you went through the math (and I haven't) that fight (if unchanged) was about an EL 30 or so...changed that would go probably go up past 32 or 33.
To be clear, I am not upset about the changes made...well, maybe I am a little bit discouraged about the final outcome, but that is more because of the collective losses of the last two AP's and is not directed at our DM in any way. But, considering how well we have done through a majority of this campaign (drafting the plan that allowed us to punk Dragotha being my crowning achievement) it was a lot of fun. A wise man once said (paraphrasing), "It is not always the destination that matters most; sometimes it is the journey to get there."
As far as Demogorgon goes, JD has promised not to adjust that encounter and let the chips fall where they may, so I feel confident that our intrepid heroes (or more appropiately, anti-heroes) in the Savage Tides will be victorious. Stay tuned!