From the introduction: Beneath the Crystal Caverns is intended for four characters with an average party level (APL) of 8. Characters who complete this adventure should earn enough experience to reach halfway to 9th-level. A malevolent monstrosity is assaulting a town deep in the snowy mountains. This campaign takes place in Arden, although it can be set in your own world. Any party composition should be able to finish the adventure with intelligent play.