Magus is very useful, since in the end of the game I don't use much double/triple techs (It's very useful in low levels, cuz in the beggining it's stronger than single attacks, but at the end of the game, in most cases, you are wasting one attack). And Dark Matter is a damn good attack.
As a character, I think Magus is one of the greatest RPG playable characters ever... Maybe that's why I almost never kill him.
