Originally posted by Darth_Glentract
What do you think he did in the many years he was on Malachor V? And the opportunity wasn't totally gone, as Sidious knew Sith Magic.
He obviously didn't learn enough to confront Traya or Nihilus and I doubt that he can keep parts of his body where they are if they are cut off. Obviously he has just one eye and is physically blind which shouldn't be the case if he can do that.
So Yoda and Mace are pretty likely going to cut him into nice pieces but they would probably go down at NJO Luke or Kun - I don't know.