Cloak of Fear is VERY effective if you slot it 3 Fear, 2 Acc, 1 End.
The Triple fear makes the fear last twice as long, plus I'm pretty sure it stacks. So, in about 10 seconds, every minion in the group is cowering for the rest of the fight, while I fight the LT's and bosses. Thanks to Death Shroud, Dark Regen and Dark Consumption, engaging a mob WITH a boss gives me better odds than fighting a boss alone! Yup. I eat people.
Plus it looks insanely cool to your teammates when you run in to a mob without taking the alpha strike (Cloak of Darkness) and they're all paralyzes with fear, and you solo the whole mob.