The shade was a chilling creation; Mayor Me made a deal with this ominous force to keep the peace in the sanctuary. Anyone who broke the rules - be it stealing medicine to killing another - was marked with a tattoo that counted down to their death. When they faced the raven, the Shade took the soul he had made a deal for; only Me could take it back. This terrifying force lurked within the peace of the sanctury but the question remains for how long> Had Ashildr been using the Shade to enforce peace for the last two hundred years? Or was it more recent? Most importantly, is it linked to the series' big bad or is it the unfortunate means by which Me lured the Doctor in and sent Clara to her death?