Origin
When a Victorian magician created a new magic trick, he unwittingly opened a portal to another dimension. The trick was walking into one mirror and walking out of the other one. But in fact, the people walking into the mirror were transported to another dimension, where they were quickly imprisoned and their mind’s energy drained by shards of Spherion crystals. Their mirror image walked out of the other mirror. Thus the mirror image of the magician named himself Silversmith.
Harvesting humans by giving away free tickets in 1866 Edinburgh, the Silversmith challenged audience members to perform the same trick. The Doctor and Josie Day witnessed the event and went exploring. They discovered the mirror to be a portal and, chased by the Silversmith, walked into it. They freed the captured humans, even the original magician, and walked back through the mirror. The mirror images can’t live in the same world and were thus sucked into the mirror, back to their own dimension. The Doctor destroyed the portal, locking the Silversmith in his own dimension.