5 items: Dealing direct damage to an enemy places a ghostly curse on your enemy for 6 seconds. Cursed enemies take 617 extra damage from all of your damage abilities. This effect can occur once every 9 seconds.
Reading the descripotion, i'd expect it to proc on multiple targets with a seperate cooldown on each of them.
So i tested this set yesterday, since i thought it would work fairly well with grothdar and elfbane on a magDK. Test shows that only one target can be affected at the time. I just wonder if this was intended.