Caverns of Chaos is a themed dungeon supplement. Using the core rules in Four Against Darkness and Four Against the Abyss, you may use this small book to generate new missions, meet new monsters, and collect new treasure. The booklet includes six missions, new vermin, minion, boss, weird monsters, treasure and unique event tables, three new dungeon secrets, six new spells. Attention: this is not a stand-alone product. You need a copy of Four Against Darkness (and for some of the content, Four Against the Abyss) to use this book.