There are those who have the ability to work them selves into a frenzy for combat. To work themselves up they inflict a small amount of damage onto themselves. Once in a frenzy they cannot flee from combat but because they are focused on killing their opponent they do more damage when they have successfully struck the opponent. Whether or not they successfully work themselves into the frenzy they will take the damage they inflict on themselves. Normally it takes a short while before the berserker is able to try again.