TBN is a weird one, on one hand it is strong when dealing with tank busters, on the other hand, it is terrible in dungeon pulls, popping very quickly and essentially 'ending early', whereas, with other short cooldowns, they have some sort of mitigation that lasts the full duration.

One thing that could be done, that is a bit unique, would be to provide mitigation for a duration once the bubble has popped, where the duration is equal to the time left on TBN.

To make this a but clearer with an example, if we extend the duration to 10 seconds, if the initial shield pops at 3 seconds, you get 7 seconds of 15% mitigation, pop at 8 seconds, 2 seconds of mitigation. etc.

This also comes with the benefit it becomes more helpful for multi hit attacks.

For something that costs MP, (which does become damage neutral at minimum as long as it pops), it lacks that little something compared to the other short cooldowns.

Now, my DRK is still 90, so i have no experience using it in newer content, but this is something I felt was off when I was using it at lower levels.