"Union and Disillusion" is the fourth Mythos Pack in the Circle Undone cycle for Arkham Horror: The Card Game. It takes players to the mysterious Miskatonic River and the small, foreboding island known as the Unvisited Isle. In this pack, players must explore the foggy shores and dense forests of the island, using all the skills and abilities at their disposal to uncover its secrets and save the world as we know it.

The Union and Disillusion pack introduces new mechanics focused on movement, as players navigate the dangerous terrain of the island. Guardians can use the new Warning Shot card to push non-Elite enemies away from their location, giving them time to escape or regroup. Seekers can use the Esoteric Atlas to move quickly between locations, allowing them to explore the island and uncover its secrets at a faster pace. Rogues can use the Decoy card to save any team member from danger, no matter where they are on the map.

As players explore the island, they will encounter a few helpful allies in the form of ghosts, such as the Guiding Spirit. These allies can provide valuable assistance in the players' quest to unravel the mysteries of the Silver Twilight Lodge and the strange pillar of light that hovers over the island. However, players must be careful, as the island is filled with danger and unknown terrors. One false step could lead to disaster, and players must use all their cunning and skill to survive. Can you uncover the secrets of the Unvisited Isle and save the world from the forces of darkness?