With the Fury Rune the Berserk status can be purposely and permanently inflicted upon its bearer. In this state the bearer gains enormous strength, though at the cost of being consumed by rage and randomly attacking anybody who stands in his way. Whether or not this can be used in a positive way is dependant on the situation.
The lizard warrior Dupa is at all times equipped with this rune, which makes him an unpredictable member of his clan. The Fury Rune is scatteredly found in nearly all parts of the world, but still a bit rare. - Celes