You need the Passion Necklace for this. Max out the Passion Necklace to get the Full Power Skill. This will give you a winning advantage if you leveled up frequently. To insure victory, be at about level 51. When you start the battle with the monsters, guard and take them out with normal Arts. When you defeat the last monster, Gorva, the black swordsman (Rauss) will appear. Go into guard mode, taking a full rounds of attacks. If you leveled up enough, this should only damage you about 450 health. Then, attack using normal Arts. After that, he should use his Ultimate Fang attack, causing extra damage (200 points). When you survive the attack, guard or heal, use Sky Fang and Thunder Sky to deal ultimate damage, and should take him out. If he is still alive, you can guard and take him out with normal Arts or just use Galea. Using Arts is recommended, as Rauss will cut Galea's damage by half. Also, you must equip the Full Power Skill.