Sin’s Fusion Fuse

A small quasi-mechanical component embedded in Sin’s chassis, its silver casing etched with heat damage lines. When exposed during battle, it glows faintly, identification plaque peeling off. The Doctor seizes an axe—disabling the extraction device to free Leela—and strikes the component last, just before Sin’s barrage forces desperate cover. Greel’s ritual heats Leela’s body, the Dragon’s Sin enforcer’s hold weakening as Sin finally turns traitor after firing at Greel.