Ever wondered if there was a secure way to carry messages, how to drug someone's wine while sharing the same jug, or what damage explosive rockets would cause? Wonder no more! Cardinal Richelieu reveals a number of wondrous devices, from tools of subterfuge and deception to new weapons through to fantastical machines, such as the aerial screw, armored war wagon, and submersible boat! This work is intended solely for Gamemasters.