Superstition

Superstition is a  passive skill in Diablo III, unlocked at level 30.

In-game
Damage reduction is multiplicative with other similar modifiers.

Chance to gain Fury depends on the type of attack in question: solid single-target hits have up to 100%, whereas damage over time and area of effect damage have significantly lower chances, to keep the Fury income at the rate of roughly 2 per second per source of damage.

Trivia

 * The object depicted on an icon is a stereotypical rabbit foot, which is a superstitious charm for good luck.