Aerro is absolutely right if you are talking about 16m HM TFB. There is no way to kill the final boss TFB without the best possible itemized gear and augments. Even with the best gear going into the final boss, you will be hitting enrage every time.
8m HM TFB, specifically the last boss, seems to be tuned easier than 16m so you could probably get away with slightly less than BiS gear to get 5/5.
Are you referring to the enrage of each tentacle phase? Or is there a timed hard enrage for the boss?
We will try to tackle 16m when some of our away members return. So good to have an idea going into the fight.