This is a personal, largely spoiler free (or spoiler-vague) review of the fan-made scenario Pictures at an Exhibition, part of the Mythos Deviations collection by The Beard for Arkham Horror the Card Game.
The Mythos Deviations are a collection of scenarios design to be added into the existing official campaigns. Pictures at an Exhibition can be played as part of the Path to Carcosa campaign, after A Phantom of Truth (5th scenario) or The Pallid Mask (6th scenario), or as a standalone scenario or side scenario as normal. In Pictures at an Exhibition, the investigators are delving into a mystery surrounding an art gallery that might be tied to the King in Yellow.
Pictures at an Exhibition slots into Carcosa by focusing heavily on one of its key components - hidden cards. Both new and existing hidden cards are at play here, as well as multiple effects that change based on how many hidden cards you're holding. Many of the new hidden cards aren't too bad if the right character draws them, but still need to be dealt with regardless due to all the other mechanics in play. This leads the scenario to be all about action compression - if you have the actions to take out hidden cards and still get ahead, you'll be fine. But if you were planning on shrugging off the mythos deck by passing revelation tests, you'll find it far less useful here.
This bogging down fits well with the main threat you're trying to overcome - locations you need to gather clues from to unlock the ability to fight an enemy that slowly grows in power every time. Beat it enough times, and you're off to fight the boss monster - that makes clever use of Conviction and Doubt mechanics, as well as a good way to involve both fight and clue focused characters. It doesn't have a lot of flash to it, but it's a solid scenario that makes sense to fit in between some of Carcosa's weirder ones and gives Conviction and Doubt a way to matter more to scenarios themselves.
With a 19 XP party, I found Pictures at an Exhibition to be of a good difficulty level, although any sort of action compression is going to be a big help - expecting to get by on spamming low value tests will get you tripped up.
Pictures at an Exhibition is a fun scenario that's worth checking out, and while it's not as elaborate as many of the official side scenarios, it feels like it could have been a normal Carcosa scenario naturally.
Rewards
Scenario Cost: 2 XP, or 1 XP as part of a The Path to Carcosa campaign
Potential XP Gain: 1 (locations) +1 (Corisande Malinvaud) +1 (Beast of Aldebaran in the enocunter deck) +1 (successful resolution) = 4 XP or 2 XP after cost, or 3 XP if part of a The Path to Carcosa campaign
In addition, on scenario success one investigator may choose to add The Gilded Palette to their deck. You may also choose to gain one bonus experience (counted above) or remove 1 Conviction or Doubt and gain 1 of the Other.
More on Mythos Deviations:
Mythos Deviations: Overall
Lines of Reality: Review and Rewards
Pictures at an Exhibition: Review and Rewards
History in the Making: Review and Rewards
Event Horizon: Review and Rewards
The Labours of Hypnos: Review and Rewards
The Wreck of the Albatross: Review and Rewards
Mythos Deviations Investigators