In the Clutches of Chaos is the fifth Mythos Pack in The Circle Undone cycle for Arkham Horror: The Card Game.
After your fateful investigation in Union and Disillusion, the state of the city continues to decay. Breaches in reality begin to rip through the fabric of the Earth, and a faint melody of discordant pipes can be heard throughout the streets of Arkham. Frightened citizens have sealed themselves in their homes, yet you continue to patrol the streets, desperate for some solution to end the chaos.
In In the Clutches of Chaos, doom does not accrue at the usual rate. Instead, breaches are made at various locations, marked by resource tokens. When enough breaches have been made a single location, an incursion occurs. An incursion adds doom to its location and causes the breaches to spread, opening rifts in reality at connecting locations. Your goal is to prevent incursions by removing the breaches that cause them, but this can only be done by activating the action abilities on each location. If you do not maintain control over the breaches, you may soon find yourself overwhelmed with Arkham falling into madness. You cannot allow that to happen!
—description from the publisher
Mozzik
Now this is a unique scenario! It's also Pandemic... like, it's really, really, Pandemic mechanically. Unfortunately, it's also fairly random and it can snowball unexpectedly and HARD. I've only played it once so far, and it was a dismal failure. Update: Having played this a few more times it remains, literally, pandemic. It's very swingy and the player count scaling is odd, but it avoids many of the memory issues that plague this campaign and there's zero chance you'll mix it up with any other scenario. Those are both big pluses in my book. The player cards are a particularly good blend where almost all of them do something new, unique, powerful or a blend of those. These are cards worth spending xp on (Also, Trial by Fire is a standout zero cost card).
Bayushi Sezaru
Arkham Horror: the Card Game is an awesome crossover between RPG and card game, thriving in atmosphere character development. No need to point out that expanding the card pool (both with new scenarios and new investigator cards) is a great way to keep it fresh and enticing! In the Clutches of Chaos is the fifth in the fourth cycle of Mythos Packs, and contains the seventh scenario of the Circle Undone campaign. In addition, of course there are a few new tasty player cards.
Epava
Love the mechanics here, especially the way doom is managed. It is random but it never feels frustrating. The only thing you need is a random number generator because you will need a quick way to select random locations.