You will Get this by playing the game. This is the Boss you fight at level 10 of the Cave world.
How to defeat this boss: You can only damage him by jumping on his head and every time you do this he gets redder and redder. Once he is hit he will fly up and shoot balls at you this will start off as one then later he fires 3 at once so this becomes a bit of a dodging game. Then he will fire Shurikens at you (4 sided blade that ninjas are known to use) dodge these and try and get a shot on his head whenever you can but watch out for the 'drills' on the sides because they can catch you off guard. You only need to hit him 4 times to defeat him.