After you beat the game become as evil as can be. Then go to Cliffside path going toward barbate prison and undead will come up two at a time and not stop. Use physical shield and fight until you have 200 combat multiplier. Then teleport to the guild and buy berserk. Then level up berserk to level four which masters it. Now use berserk and while you are transformed save theme. Then quit and reload and you will be transformed until you use it again.