I had try to use Raegar MB in many situation
In PvE if not for bonus stat his aura is weaker version of Sora, he skill not that useful unless he change to his celestial form, but he didn't silence boss often or maybe I just got bad luck?
In PvP (expert+) at first I though his skill would be great for my team since I use 2 mage, but in reality,
vs tank team
- after decrease guardian mag, only manage to damage with skill 2000 more it not much to guardian
- silence is nice to have but still hard to use and it didn't 100% chance, if I miss I lose
vs Ranger team
- die before he can do anything but well some time it nice to use him as decoy
vs Mage
- well he is mage bane so of-course he work well in this situation, -70% mag to very much and my team is kind of high def and mag to begin with
when face Ronan or Talissa their skill lose so much damage but then again...I rarely lose to Mage team and now a day it even more rare to face mage team
In Raid
I might be mistake here but it seem he some time can silence boss, but still hard to use since he need to change his form first
In conclusion I try many way still don't know which way to made him one of kind that can't replace by other unit, cause every thing he can do, there are other unit can do better