Berserker Rage

Berserker Rage is a  passive skill in Diablo III, unlocked at level 20.

In-game
The bonus is determined by the Fury present before the attack occurs. Thus, an attack that starts above the threshold but causes Fury to fall below it will receive the bonus, while an attack that starts below the threshold but generates enough Fury to end above the threshold will not receive the bonus.

Trivia

 * The description is a quote from Incredible Hulk TV series opening sequence (1978). Similarly, Bannar the Berserker is named after Bruce Banner (Hulk's human name).