I say this with almost every entry to the point I am considering just typing up a boiler plate start to save myself time. When scaled to page size, this is basically unreadable for me. The sharp contrast on most of the pages means it is probably going to print clearly, but I'm going to be holding this up to my face or putting on reading glasses. Packing a lot in comes at a cost. I hope the gains are worth that cost.
The artwork is evocative and wild. While it's not to my tastes as a style, I recognize it evokes a lot of questions and a sense of the uncanny. I find myself with a lot of questions looking at it. At the end of the day, an image that leaves the viewer wondering more about the situation drives eyes forward, so a success.
While I have read a few Cairn modules, I have never played Cairn and am by no means an expert. As such, take anything I say relating to statistical elements and game play with a grain of salt. I'll do my best to make sure everything is useful despite this fact.
Right out of the gate, you start with a set of paragraphs well suited to the cover copy of a book one might find in the Appendix N. Solid choice and offers up a clean bit of information about the situation that will serve as our plot hook. Right after is an offer of two clear methods of reaching the target. One obviously easier than the other at the cost of having to spend a good bit of time and effort climbing. The other is quick, but would require irritating the town officials and possibly risking arrest. Solid again.
Under 'what's really going on' there's some serious setting specific name dropping. That said, I didn't find it hard to follow. Only found one word I think lower vocabulary folk might trip on, but it was pretty clear from context what it was. I doubt it's going to be any real issue. Overall, it sums up the situation in a small space. Good. Tight prose is one of the most difficult elements of writing, but it felt like I had pretty much everything needed.
Gnoll priesthood is not something I see every day. They're the ones we are helping. I keep rolling it around in my head like a set of rusty gears grinding together. I wonder if this is kind of like how kobolds still exist as a different sort of creature in my head than they do in many of the current TTRPGs of the world. Do I have anything useful to say about it? No. Just pointing out how jarring this was for me personally. It creates a sort of wild and unexpected situation right away.
NPCs are pretty clear on the Naka clan. Having the ability to possibly read and even alter fate is interesting. It's especially good that there's a high price for doing so. Saving freely on a single save can make or break you sometimes, but then having to evade spectral gnolls for a week could be rough. That's a good balance of an easier time in the present for a harder time in the future. The question is does the person taking that action now realize there is a cost for it later? Not entirely clear. Possibly some sort of religion or knowledge check. Not sure if Cairn has those.
The enemy and his groupie are interesting enough. Clear outline of how to handle things if the party fails and not going to lie, I empathize with the 'bad knees' element of the enemy. Critical damage is especially nasty here since it can make allies into enemies. Extra brutal if it's a party member. The blink dogs are interesting due to the rivalry element. That said, you note 'this Area' as being a location to drop and take damage in. Because of the wording and bold, I was thinking at first it was going to be a hyperlink to a specific location. I would reword it as 'the currently occupied Area' or something similar. Just for extra clarity. Also, what happens on a 10? There are 9 areas and we are rolling a D10, so is that GM's choice?
Respawning enemies feels a little 'gamey', but nothing egregious. Explains where they keep coming from on a limited map, so there is a solid reasoning here. As to the elementals, this creates some interest as well. If I have one complaint, it is that you don't follow your own convention here. Elsewhere, you reference the number when mentioning a specific location. This time you just say spire. While some will immediately recognize A9 as the spire, others will not immediately associate the name of the mountain with the reference here.
I say as part of the 2 year folder concept. If I pull this out of a folder 2 years from now, I am probably skimming it and remembering the basic idea, but might skim and miss the name of the mountain earlier in the document. Adding that little (A9) just makes sure there's no flipping around trying to figure out what I missed elsewhere. Well, that and some people just miss things.
Encounter list seems short, but not knowing how commonly it is going to come up in the system, that might just be me. Having repeats create new body parts is a good way to avoid constantly seeing the same event on the encounter list when it is this small. Nice. Map is pretty and easy to read, so may as well comment about that as well.
Area 1 is fine. I feel like the elevators returning to the city is an easy escape for someone stealing a book. I'd rather see them instead be locked to the location. Doing this could actually create an interesting option to gain the elevators that were locked below. If they climbed the path, but end up here, the book opens options. Take it out of the building to cause the elevator to lift and break the chains to return. Then put it back and boom, new escape route!
A2 is good. Not an easy situation to resolve, but a reasonable reward if they do. A3 is hard to get to, but offers some interesting things to interact with. Having a plant being caused by the garden who isn't allied to it is fun. I can see this getting played different ways to suit a group. For players who are a bit silly, it could be a moment of levity. For those who are into brooding things, it could be learning of a child without parents and no understanding of the world it exists in. It could go a dozen different ways to suit the needs. Good. Very good.
A4 is clear enough. Setting and vibes. A5 offers a choice between food for the allies or a very valuable pet for the group. My only question there is if the Egret is smart enough to have conversations. It seems to be implied it can happen, but it also seems unlikely to be speaking a common tongue. I am going to assume Cairn has some means to communicate with animals for this effect.
A6: Somehow the second time in this jam I am seeing giant silkworms. Quite unexpected. Surprisingly large number of things to explore and a bit of storytelling here with the wrapped body. The item being a jack-in-the-box that's actually a folding glider feels a little out of place. Glider offers another means of traversing which is good. Just not sure about the jack-in-the-box aspect.
By the time I get to A7, I have gotten a ton of locational storytelling. Every location says something about what has been going on, what's currently happening, and where the story is going. It means no matter where a player goes, they gain something about what needs known. There's no reason they have to hit any single location so far, but doing so benefits them. There's no pattern they need to follow either. This is good for any map.
Nothing to say about A8 really. Clear enough. The peak stuff is pretty clear as well. Everything has been laid out on how to do things. My only question about the entry is the fruit. Eating them (god why) prevents a regrowth, but what if someone just chucks the fruit over the side? Does a new one form? Also, now at the end, I am wondering where the side path leads. Obviously it's the long route from below, but it goes around the back and none of the locations indicate if lets out into them.
Based on the intro, it leads to A9, but that seems ... bad. I think having it come around the other side and let out into A7 somehow seems to make it a bit less 'strait-to-the-baddie' in nature. Given A1 was pretty clear no visitors are allowed, it seems similarly odd this spot lets people walk right up without anything to stop them.
Anyway, if my worst complaint is just being concerned the players might face a villain a little early, I am doing well. I've never had inclination to stop players from face-planting (see what I did there) right into the enemy fist. I don't love the art, but that's just my own aesthetic style preferences. In terms of what art is there to do, it does it. You convey elements of the story. You pay off the questions the art raises. Every bit of art is doing a job here, not just fluff taking up space. This whole thing is good. Better than I was expecting in fact. I think based on what is here, I can actually make it work in other games I do know. Since I don't know Cairn, I was worried about liking it and not being able to do anything about that fact. With the way it's laid out, I actually can convert with only a small effort. Kudos. Peak decision making on your design choices.