As told in my ongoing journal of my Rage of Demons campaign, my group just finished chapter 13 of Out of the Abyss, and I am preparing chapter 14 for the next session. Unlike the previous chapter, which I mostly played as written in the book, I find that chapter 14 has multiple serious problems, and I will have to rewrite a lot of it.

The most pervasive problem of chapter 14 is that it doesn't appear to fit with the level that the characters have at this point. My group is level 11, and as the book says that they should have been level 10 in chapter 11, level 11 seems perfectly working as intended. However most of the random encounters as well as the scripted encounters involve monsters like gnolls (CR 1/2), minotaurs (CR 3), cultists (CR 1/8), ghouls (CR 1), gargoyles (CR 2), and the like. And not in numbers that would even remotely challenge a level 11 group, even without the NPC army they have with them. While an occasional low challenge encounter can be fun to show the group how strong they are, a series of them would be boring and tedious.

The biggest event in this chapter is not much fun as written either, at it is very obviously scripted and doesn't involve any player agency. They come upon a demon lord CR 24 fighting another demon CR 17, and are supposed to just wait until the lesser demon is slain and the demon lord left, so they can recover the heart of the demon. If you play that as written, it becomes just scripted narrative without the players having any input or feeling any pride in the outcome. Combined with the low level of the other encounters in the chapter, the players might well misjudge the power of the demon lord and attack him. Any number of things could go wrong with that if you just spring that encounter on the players as a surprise. I think it would be a lot better if the group is aware of both hunting parties, the one led by the demon lord and the one led by the demon. They can then decide what they want to do about them, attack them separately with good preparation, or get involved in the two groups meeting and fighting each other. If the group themselves stages the fight between the demons, they would feel much better about the outcome.

The last event of the chapter is such a problem that I decided to completely cut it out. It involves a device called the Maze Engine, which is designed to produce a series of random effects, which are quite serious. Players could be thrown back in time to the start of the adventure, having to play through everything again. Or they could lose all magic items. A character might get disintegrated. While there are also some beneficial effects, overall the risk is far too high that if played as written a random result completely throws the campaign out of whack. Again this is a problem of player agency: They can't know the possible effects of the engine, and they can't easily shut the engine off once activated. And other than messing with the group, the event doesn't have any real function within the overall story.

So now I am rewriting much of this chapter in order to make it both interesting and playable. But I think the underlying problem is that D&D in general gets weird in the second half of the level curve. "Random encounters" that challenge a level 11 group don't make much sense, as the monsters you'd need for that were designed more like boss mobs. With a group that powerful, it is better to just skip the small stuff, and only really play through the main encounters of the book to the end.