What if there were spells (or even applied to all spells?) that made use of tp for extra damage similar to SMN blood pacts? Did some quick mathing, going to try to explain this the best way I know how since it's already 6:30 am...

Tier of Occult Acumen determines TP gain from % of MP cost.
So BLM90 with Occult Acumen I casts Bliz5 and gains 7.05TP.
My idea, take the tier % of your current TP, and use that as bonus damage to spells. So 2.5% of 7.05% TP gives .0017625 bonus damage. So take final damage (or wherever you decide to put it in the equation) and multiply by 1+.0017625. It's a small bonus, ~7% damage increase @300TP, but that would make it unbroken I think. Keep casting same element spells (so you don't have to switch staffs) till you have 100+TP then cast another spell (of the same element...again for the staff) designed to use a larger part of your TP for extra damage that then resets TP.

Again, just an idea that was concocted at 3am...when I should be sleeping...