2004 · ソースブック（プレイを拡張するルール／オプション）

First Book of Things

A collection of new creatures, technological items, and spells for the Call of Cthulhu role-playing game. The creatures include both Mythos entities and other horrific foes, giving Keepers additional threats beyond investigators’ existing knowledge. Strange technological items are associated with several of these beings, while the included spells focus largely on summoning, binding, and creating new horrors, and are most often used by opposing forces.