My thoughts on the Chamber of Eyes, that I've done so far: My party handled the strategic element of it quite well, spitting up the fights strategically and choosing the back route, even if they didn't quite do it on purpose. They avoided the stone doors with the mark of the Bloodreavers on it. They still haven't figured out the mark I planted, which handily coincided with the guest appearance of an extra PC in the party. This mark on the temple of the cleric, which is supposed to be a branding that he received after being sold to the duergar. I plan to introduce those marks on the duergars' weapons when they reach that combat later in the Chamber of Eyes, in addition to on the Grimmerzhul Trading Post sign when they go back to the Seven Pillared Hall.
I'm having an ongoing experiment with how to portray rules situations in more than their straight rules formats. For example, I'd rather say, "The duergar's skin glows as your fire breath courses over him and it seems to have no effect. He has fire resistance," as opposed to, "Your attack only deals 3 damage. He has resist 10 to fire."
In addition, when it comes to the encounter with the duergar, I was thinking of modifying a couple of their powers. For example, I think the beard quills power is a bit silly. I was instead trying to make it a bit more demonic and menacing, enforcing that they were demon dwarves instead of just weird looking ones. I want them to feel a little different than "just another humanoid".
I'm also worried about them tactically neutering the last encounter of the Chamber of Eyes. This is one that I've always found to be a good one. The dire wolf, the double-levels with the archers, and the chief make a nice climactic fight with the reward of a couple rescued slaves at the end. However, if they come around from the way they are headed right now, it'll turn into a bunch of archers lined up, waiting to be destroyed. The dire wolf plays no role, and it's just boring. I'd love some advice on how to subtly steer them back on track.
Also, I plan to cut out the incriminating documents and replace them with other clues as best I can, because I think it's a little overused in the Wizards published adventures. Also, it makes the players feel better if they figure these things out for themselves.
Last point - I'm going to introduce Brugg the ogre on their next trip into town, and I'll also try to point an arrow towards Paldemar, the main villain of the adventure. Failing that, my goal will be to make them hate all of the slavers as much as possible - that way, when they find out Paldemar is behind it all, they'll hate him too. Since the people who live in Fallcrest were taken by these slavers, they have connections that they value. Any advice would be most appreciated.