I'm a bit confused about Dark Arts so please correct me if I'm wrong.

So we use TBN, and if it's broken then we get DA, which gives us free EoS/FoS.
TBN costs 3000 MP.
EoS/FoS costs 3000 MP without DA.

so basically using TBN doesn't really change the number of EoS/FoS we can do, nor does it effect our DPS in any manner (if we're doing it right).
Except if we're doing it wrong and ended up losing 500 potency or worse.
is that correct?


Like, I understand if I "need" to use it for mitigation and will definitely do so if required, but why would I want to use it otherwise?
Considering the high risk of it not breaking, wouldn't it be better if I just not use it at all most of the time, and keep my precious 3000MP for risk-free EoS/FoS instead?



GNB's barrier is simple 0-cost ability, so I wouldn't mind using it cos nothing to lose anyways, but
TBN....?