Arkham Horror LCG: Heart of the Elders Mythos Pack
Arkham Horror LCG: Heart of the Elders Mythos Pack - Rules of Play says:
This Mythos Pack features an immersive two-part scenario that takes you on an adventure both above and below the Earth. Immediatley forced to face the consequences of your choices, you shape the scenario as you go, determining which dangers you face and which allies you rely upon. Isolated from the rest of civilization, who can you trust?