As his nemesis, we have Commissaire Lohmann. Hearing his name only will make the criminals tremble.
For a sequel, I think the story is very well written. The original Dr Mabuse was a hit, a classic; so I am glad they didn't change direction for this sequel. The doctor stays mad and another person follows his path by taking his legacy. Same like Dr Mabuse, Dr Baum do his crimes to terrorize the world. He likes to spread fear, he doesn't want money. It's scary, really, when we cannot negotiate with the bad guy because he doesn't want anything but our fear.
Dr Baum doesn't really hide behind the screen. When one of his thugs - Kent- rebels, he finds that behind the screen there is only a microphone/radio, a desk, and a carton silhouette. I think somewhere in the movie, a thug dies for trying to find out who is behind the screen, so why Kent gets lucky?