Is TBN a bad skill?

[NarutobandHD]

I would say it's closer to bad in the sense of if the boss is too weak to pop it in the opener, like in E6s, your opener gets completely messed up and it's simply out of your hands. Now if it worked like SAM's Third Eye where the effect pops on any hit, then it would be better but still not great cause then you'd end up using a Dark Arts charge instead of Mp in the opener which would lead to overcapping. So then Dark Arts would also need to be changed to be used on something else entirely. It's kind of a mess.

[Absurdity]

I would say it's closer to bad in the sense of if the boss is too weak to pop it in the opener, like in E6s,

You could always take off your gear, put TBN on yourself or your co-tank (who would have to be naked in that case) and put it back on right before the pull. TNB scales with the HP your target has at the time of casting it so no gear = less HP = lower shield.