A Freeze Gas and Hide are required. First, throw Freeze Gas on your opponent(s); then Hide for as many rounds as necessary for the opponent(s) to sneeze themselves to death. Even the best opponent (legend) can be defeated in this way. However, this may take up to (150-15)/10 i.e. 14 rounds; weaker opponents are finished off sooner. When you do this, even if you are outnumbered and/or very weak you can still kill really strong opponents while guaranteed that you get away unharmed.