Haer'Dalis was rescued from Mekrath, then everyone took a deep breath and went to the planar prison...
The opening area was a cake walk. The next area with the two thalls was even easier.
Then things got hard because of stupid AI pathing.
The plan to handle the wyvern and salamanders and yuan-ti mage with web/cloudkill. What really happened was this:

Shea dead, Vanja and Nalia nearly so, and Isa nowhere to be seen. It all started well, with Isa and Nalia getting off thir web/cloudkill combo. Then Vanja and Shea were supposed to move up and block the salamanders from exiting the webs. Vanja got into position but Shea...got warped into the prison cell with four 'warriors'. Who immediately slept her and killed her. And then came out of their cell to attack Vanja. Nalia and Isa went invisible; Yuan-ti mage -- for the one second it *wasn't* held by webs -- used true sight. Then chaos. Isa failed her save, wandered off to the left somewhere. Vanja is now soloing four warriors and two salamanders with Nalia providing cover fire with arrows. The salamanders, thankfully, are too stupid to move out of the webs, so they are periodically held, yuan-ti mage spends most of the rest of the battle held along with the wyvern. Cloudkill slowly eats away at their HP. Yuan-ti mage fires off skull traps. Warriors go down, finally. Vanja quaffs potion of xtra healing, continues to slug it out with the Salamanders. Web wears off. Wyvern closes in as yuan-ti mage fire off it's second skull trap. Wyven and salamnders go down. Vanja and Nalia finish off the yuan-ti mage just as Vanja's second rage expires.
We head north to take on the pair of thralls; this time Nalia gets hit with chaos and alerts the master of thralls. He sends his air elementals to deal with us, we deal with them, and then go after him.
Yeah, sorry master of thrall, Vanja doesn't care what you throw at her. She's going to kill you either way.

All done. And now Shea has a shiny new staff of air! Woo hoo!

Um, at least it was the same one they fell into before... stupid pathing

So we destroy the ball thingy that controls the thalls, sit back, and wait to see how things play out.
...
Wait, what? Huh, never seen that before.

Mopping up the last of the salamanders and yuan-ti. (Those mages sure to love to commit suicide with skull traps).

Sure you can Raelis. I'd accept gold, or silver, or platinum, or your first born...

Edit: And woo! Isa gets her first 6th lvl spell: PW:Silence.