A high powered 4 DOF prosthesis for transfemoral amputees is presented in this paper. The prosthesis utilizes series elastic actuators with high powered hobby grade helicopter motors capable of providing 2880~W of power each for knee and ankle pitch and ankle roll. In addition, a yaw motor with a planetary gearbox combination is used for yaw actuation providing up to 21~Nm of torque. The prosthesis was designed to accommodate a variety of activities including, but not limited to, walking, running, and stair climbing.