If you were referring to the fight between Liu Kang and Shao Kahn at the end of the Outworld tournament, then here is the way to do it for those of you who are not past this point. Not only can his block not be broken, but you can not damage him unless he is not attacking. Therefore this leaves him with one weak spot: when he's taunting you. The cardinal rule in this strategy is to keep as much distance away from him as possible, as his dash and hammer attacks always break your blocks. Once you are keeping your distance, the only attack he uses is his long-range projectile attack, which are his spears. These are easy to jump over if you get your timing right, which is preferable to blocking and taking reduced damage. I say this because the endgame in this strategy is having the timer run out with his heath being lower than yours. Now for the offensive and key part. When he is taunting you, use your fire ball or flying dragon kick (remember, from a distance!) to damage him. The dragon kick does a little bit more damage, but the extra risk is that you must then jump away before he gets up. Keep repeating this until the clock runs out, remembering to keep your distance, and only attack when he taunts you.