Vade Mecum is a necessary component of the CthulhuTech experience. It includes rules for Xenomix characters, the children of the Nazzadi and Humanity, as well as Para-Psychics, a class that probably should have been in the core book. The decision to leave them out of the core book was not based on greed, but rather based on not initially intending for the character types to be playable characters. After several protests (and begging sessions) from the fans, Vade Mecum was released with the material. These two additions to the plot add depth and conflict just by existing and can only add to your game at home. Also included are new Aquatic Mecha for every faction, new classes, new enemies, new optional rules for a more painful combat experience, martial arts rules, and new adventure outlines. Translated from Latin, Vade Mecum has two translations: "handbook" or "useful thing." This book was quite aptly named.