Amtorian jiu-jitsu

Amtorian jiu-jitsu was a method of martial arts known to the Doctor. It was considered to be a dangerous practise, as even watching it could cause headaches, nosebleeds and much worse.

Like Earth martial arts, skill level was denoted by colour sashes. The highest level was denoted by a purple and puce coloured belt. In order to get this rank, the trainee would be attacked at any time to see if they could defend themselves. Though the Doctor was good at Amtorian jiu-jitsu, he never took the challenge for the final rank. (NSA: The Story of Martha: Star-Crossed)