TBN is fine. Play it right and you can be insanely tanky and significantly reduce the amount of healing needed on you whilst not losing a lick of dps. It is an excellent ability and the decision-making element to it is engaging. You get rewarded for learning which attacks you can successfully break the shield on. Predicting damage and smoothing it out by preparing accordingly is the absolute pinnacle of tank gameplay.

The fast cool down is amazing and I am finding it extremely useful in EG savage. Using it on the main tank pretty must ensures safety through tankbusters. The MT never gets left dangerously low even with no cooldowns due to how powerful TBN is.

For double busters like spear and shadow flame you can use TBN such that only the off tank takes damage, which massively reduces the demands on healers.

TBN needs to stay exactly as it is.