Hey, I’ll be very quick here: I think you should create some Arts for flame skills like Pyromancer’s and Elementalists’s ones that could change de colors of their flames and also give 'em special buffs.
Blue fire: add holy property attack to fire skills
Purple fire: add psychic property attack to fire skills
Green fire: add poison property attack to fire skills
Black fire: add dark property attack to fire skills
Beyond the fact that it would be a beautifull addition to the game design, it also open a lot of new possibilities of builds!
Well, I really dream with a blue flame Pyromancer or a Warlock that can control dark fire!
That’s it, thanks!