Instead of making it time based, it should be "charged" as you perform BR on a specific target. This way people cannot farm it for a boss fight/instance. In addition to greater dmg/effects of these new abilities, I'd also suggest that they unlock a second tier of BR (ie: BR of these new abilities) which will make certain high end boss fights easier but not game breaking. For example, one of such second tier BR can significantly lower physical defense for a super-admantoise HNM for a short time period.
This way, it'll promote party interaction and tactics. For example, players now have the options to:
1) spam their best damaging skill at TP 1k or whatever, kinda like the old way
2) they can perform BRs, which would do less damage compare to 1), to build up this new guage and solo their new "overdrive' skill.
3) even go further for the 2nd tier BR for a super debuff/dmg (then they can spam their best damaging skills).
Depending on the available skills/jobs/number of players at the field, players can choose options that'd fit best to their situation. In other words, more variety of tactics.
Edit: One example of the 2nd tier BR can be something like the one shown in the intro moving when they fight the molboro!
Edit2: Yes, they need to fix the current BR before implementing this![]()