This is the first of a series of thematic dungeons. You play using the room generation tables in Four Against Darkness, but populate the rooms with the tables found in this book. Six missions await your party. Will you manage to defeat the forces of Chaos, or will you succumb to the powers of Xichtul, the God of Eternal Change, and its monstrous avatars and servants? This book includes new vermin, minions, bosses, weird monsters, a new treasure table, six new spells and rules for chaos infection.