You have to use the skill Legacy so you can't die vs the hero cause after you take him down the third time he then uses a skill that will always kill you unless you have the Goddess Bracelet on and was at level 20 or higher (When I took him out when i did use it but i running a save without it) anyways the skill the Lion leader gives you before you die is what you need to use before you take him out the third time then after that you win the fight with one more attack do take note that you can use it at anytime but you have it's effect for five turns