nim?

Be a real man and karate chop the living crap out of him. Then let me know if it works.

Like so many of the bosses in this game the trick to beating Nim is one of avoidance. Avoid his attacks and wear him down. Keep rolling, jumping and hiding behind the pillars. When you can give him a clip full and he'll go down eventually. It's more of an annoying grind than a real challenge.