From the introduction: Swamp Thing is intended for four characters with an average party level (APL) of 9. Characters who complete this adventure should earn enough experience to reach halfway to 10th-level. Goblins have been kidnapping passersby and sacrificing them to a hydra in the swamps. 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.