Robe of the Corruptor

(2) Set: Increases your Shadow spell damage by 35 and your chance to critically strike with Fire spells by 3%.

(4) Set: Your periodic damage effects have a chance to trigger Pandemonium, increasing your damage dealt to the target by 10% (5% to players) and dealing Chaos damage over 8 seconds. Chaos damage is a combination of all magic schools, and will benefit from the highest modifier to either school.