As you progress in the pursuit of high level taichi, you will get to Chen's Taichi New Frame. This is the book that will take you through this important step - tranforming from Health to Combat. If you were nurturing your qi, tring connecting to your qi and moving your qi in the body in the Old Frame Routines, you will be learning how to apply your qi in the New Frame Routines.
However, this book is not only for the warriors, it is also for people pursuing high level of health. Have you ever wonder how taichi practicing is related to your internal energy? Grand Master Chen devotes a whole chapter in this book on Taichi and Meridians.