Fanaticism is a retribution paladin Talent.
Increases the critical strike chance of all Judgements capable of a critical hit by 6/12/18/24/30%.
Notes
Again, it's a "must have" for retadins as it increases critical hit and increases the chance to have the proc of Vengeance. With a good critical strike chance, you can reach 50% chance to crit with judgement with [Sanctified Crusader] and Fanaticism.
As of Patch 2.3, the percentages where changed to 6/12/18/24/30% from 3/6/9/12/15%