You live for combat and the kill, and when the chance comes to go for it, you and your goboys can instantly pump yourselves up to a killing fury that allows you to ignore pain, walking right through damage that would stop lesser "mortal" creatures. You still take damage, but you subtract your current Berserk skill level from any Stun/Shock rolls you make. You also have an automatic +2 bonus to any hand-to-hand attacks you make while in this state.