I didn't come away from Doom of Cassomir with major beefs about either the story or the design, and I wasn't bored, so that automatically means it beats out several other PFS scenarios I've played.
The plot here involving an apocalyptic cult (I don't think that's a spoiler when Groteus is literally on the cover) injects a dose of grit that other, overly-blithe PFS adventures could badly use. (Although the writer couldn't resist diluting it with a couple bits of cheap comedy.)
The story definitely has some things you can pick at if you stop to consider them, as other reviews have mentioned. Like exactly to what extent it's normal for the Pathfinder Society to act as an international vigilante organization solving "problems" that local governments are curiously indifferent toward. The investigation portion seemed to have some red herrings in it that are never explained. But the story isn't overtly illogical and doesn't bring up so many obvious questions that it breaks the players' immersion.
Design-wise, the biggest issue here is a situation in the latter-middle part of the adventure where the party is essentially given the option of infiltrating an enemy gathering or observing it from nearby. It SEEMS like there should be pros and cons to both options. However, in practice, I can't see the advantage to going the infiltration route, except that when the fight inevitably breaks out melee characters will have more to do. If the party has any kind of ranged damage tools at their disposal, the "stakeout" option will make the encounter a breeze because the enemy has little way of effectively responding.
Overall, there are definitely things I would change here if it was up to me. At the very least it needs some editing and additional fleshing out from a story standpoint (as is the case with virtually all PFS scenarios). But it was an enjoyable way to pass an evening.
This adventure has mostly solid pacing and encounters, some nice historical lore and story framing, and an interesting choice for the PCs on whether to trust an NPC.
Some might take issue with the "solution" to the "puzzle" near the end. Without spoiling it, there is a room which seems to keep spawning minor enemies unless you traverse it in the "correct" way. My group basically dispensed with trying to figure it out and simply muscled through, but groups which really enjoy puzzle-solving may be a little miffed when they discover what was going on.
The final encounter might be a pain point. Based on my own experiences and the other reviews, it seems like depending on the party this encounter is either trivial or very difficult with almost nothing in between. I was disappointed with how quick it went, while other people are saying they almost had a TPK? If you're running this, double-check the instructions for scaling and consider making your own adjustments.
Even so, an enjoyable adventure in my opinion, memorable for being one of the few times in PFS play where the party was actually trying to sense motive on an NPC and discussing amongst themselves what course of action to take.
This was at best a "fine" (if very straightforward) adventure until the conclusion, which really left a bad taste in my mouth.
First, the design of the final encounter is straight-up anti-fun. The environmental factors can render certain types of PCs basically useless. I understand that it's not possible to design every encounter so that every type of character build is equally useful, but it's beyond me why you would intentionally make one which will leave players with certain builds (and not weird obscure ones either) feeling like they may as well sit out. Furthermore, the combination of the terrain and the spell the enemy uses on the first round resulted in each player having to spend several minutes each round just trying to figure out where they could move, which was tedious and left everyone frustrated and irritable.
Second, the conditions for actually getting all of the treasure bundles are unreasonably harsh. It's based on how much of the cargo in the wagon you're escorting reaches the destination safely. In our playthrough the wagon suffered no damage except some rips in the canopy. However, we discovered at the conclusion that we missed out on treasure bundles because we didn't immediately and totally repair the rips. Because apparently none of the cargo of precious irreplaceable artifacts is inside crates or anything, it's just piled up in the back of the wagon like we're the Beverly Hillbillies on their way to California, with nothing but a canvas canopy so flimsy a bird can rip it open to protect it. Really?
I would be more inclined to cut some slack on this stuff if there were an engaging story framing it, but there's not. You can surmise pretty much right away "Hey, there's something in the wagon which angers or is coveted by a malevolent force" and that's basically the entirety of what's going on. There are no twists, no choices, and essentially no RP opportunities.
This is an unremarkable scenario which the designers tried to spice up with artificial difficulty that doesn't actually make the players feel challenged but may leave some or all of them just feeling arbitrarily screwed.
I have to give Mosquito Witch points for being one of the only Society scenarios I've played with an actual sense of dread and sinister mystery. Many Society adventures have an oddly chipper tone for a world where humanity's main god is dead, ancient lichs (liches?) are on the march, etc. Mosquito Witch almost feels like it was written for a different game.
On the other hand, the conclusion kind of flushes all that down the toilet. Then the final twist tries to save it but just leaves the players feeling like no questions have actually been answered after they've sat around the table for four hours.
If you have a combat-oriented party or just players who primarily enjoy playing the game for combat, this is not the adventure for you. It's pretty much entirely social RP and investigation, interrupted by one skill check "action sequence," for the first three hours or so, with two pretty easy combats basically back-to-back at the end.
Some people will appreciate MW's very different vibe. And it isn't a poorly-edited mess that makes no sense as a story like some Society adventures. Of course, it's easier to write a story with no holes when you don't actually try to resolve the story, so maybe MW doesn't deserve so much credit there. Other people will just be bored. Even players who get invested in the investigation may be frustrated at the (non-)ending.
I agree with a previous review that this seems almost like a scenario intended to demo the game to new players. Of course it actually is an intro for 2-3 more Society scenarios in the same setting, but I think more could have been done here.
The Venture Captain NPC is an interesting character, or could have been, if she did anything more than just give you your briefing at the start like every other VC in every other scenario.
The NPC's encountered during the adventure could have been interesting, but they're just kind of... there.
The puzzle in this one isn't completely nonsensical (unlike the "puzzles" in some Society adventures) and the way there are clues for solving it scattered around is nice. I can see some parties getting hung up trying to solve it all at once and never moving on to finding those clues, though.
Don't know what to say about combat balance. When I played it we had one level 4 character and then everybody else was level 1, so that may have thrown off the balance. The party also made judicious use of a consumable at the start of the last encounter. Without that and a whole party at level 1-2 perhaps there would have been a feeling of actual danger.
Ran long when we played it, to the point the GM just skipped an entire encounter. Everyone I have talked to who has played it says it runs long as well. By the time we got to the "thrilling" chase escape sequence at the end there was no thrill because everybody just wanted to go home.
The puzzle has already been discussed a lot but it really cannot be emphasized enough how bad it is. The whole table was in awe at how ridiculous it was. And we all had the advantage of being native English speakers, I pity anybody playing this who isn't.
To tell the truth, based on how much I actually enjoyed playing this 3 stars may be generous. But this scenario isn't completely trivial and devoid of any challenge like a lot of Society scenarios, so I feel the need to recognize that. If you're going to run this, put extra prep time in and decide in advance a better way to handle the puzzle (and possibly the chase as well).