To defeat Xao Gong, use the Chain Blade. When he is making clones of himself, hit him and they will disappear. To hit Xao Gong, jump and press X or B. Then, press B(2), X(4). This will take awhile. When you defeat him, he will transform to a bigger monster with five lives. After he transforms there will be a ramp leading to a higher level. Collect all five elemental weapons. After you collect them, Xao Gong will be easy to defeat because the five weapons are his weakness. Make sure you move a lot. If not, he will hit you with a blue spell that takes almost all your life away.