All these people saying TBN is DPS neutral when it breaks and very few who are mentioning that it's actually a gain when used properly. Yes on the surface it appears that you are only being refunded the MP cost with a free Edge of Shadow, but you can hold that Dark Arts proc to get an extra Edge inside of a burst window. If you can manage to do this every minute it's a pretty nice gain over a 10min+ fight. I like the skill as it is, and if they DO end up making any adjustments to it just adding 1-2 seconds to the shield duration would be enough.