Floor 16 of Spear of Destiny, titled Castle Boss, is the Boss level for the Castle chapter of Spear of Destiny, in which BJ Blazkowicz must defeat the Übermutant. The Übermutant lies at the center of the level, within a steel cage. To exit the level, both gold and silver keys are required. The gold key must be acquired by killing the Übermutant. Another group of enemies patrols in the elevator room, but they will inevitably be alarmed by level's end and brought out running.