You have to use the mirror. Once you transform into the dark world and into a rabbit, then walk near to where the bully is bouncing the ball thing. USe the mirror there and you will transform back. Jump down on the opposite side you came from and walk into the castle. When you get to the bad guy, he can hit you off the edge and make you fall to the previous floor. Try to stay on as long as you can til you kill him. Every time you leave the room he's on, you have to start over. Best advice, fall into the floor opening that will take you all the way to the fairikes and stock up.