Llamaland burped right as we were finishing off the skelly but we never really had any issues with the quest. The skeleton enchanters appeared to be CR17 or 19 I believe. This made freeing the seers trivial.
I did end up shrining for mana after the 2nd seer but I'm Torc'd and have Conc Opp.
I would class it around the same difficulty as Dust or Servants, easier than demonweb quests, just longer. No surprises for anyone who has run Madstone a few times on Heroic. Given the CR of the quest I expected it to be more difficult. It feels as if the EN/EH/EE settings really determine the difficulty and the CR means almost nothing. I probably just need to adjust my expectations to match reality.