The document introduces the communication through a video. This paper proposes a method and a set of tools for staging avatar movements that are controlled by a performer during a mixed reality theatrical performance. It refers to the field of Computer Theater as defined by Pinhanez and follows the model of the hyper-actor to control musical and visual expressive instruments in the performance "The Shadow". The focus is on the construction of the visual instrument designed to direct the simultaneous stage movements of five avatars in a virtual shadow theater. The hypothesis of using only two groups of stage actions, salient and idle, is implemented with two methods in the performance "The Shadow". We explain the theory and the programming of these methods in the Epic Game videogame engine Unreal Engine 4. The validation of the hypothesis is discussed through the artistic results of the performances. The tools for staging animations during theatrical rehearsals and performances contributes to advancing the expressivity of virtual movements in mixed reality performing arts.