On Hard and Extreme (and even later stages in Normal), Lau Wong will need to defeat Overlords quickly instead of spending time clashing. The most damaging combo is the SQUARE, SQUARE ... TRIANGLE, X combo which racks upwards of 40+ hits. If you press SELECT to change your spell to Tekkuken (the attack up spell) as you begin the combo on an Overlord, you can probably kill it in one combo (or at least rip off half its life). Similarly, you can use this technique on bosses as well. Select the defense up spell when you are clashing (or as you are being hit) to prolong your effectiveness against harder bosses.