Let them burn, summoner

I'd make it less human and more elemental. That might be hard for your style, but I think since we already have an extremely humanoid fire-elemental (Brand) if there was to ever be another he/she should be a little more dynamic and elemental. Think like Zac, but with fire; burning, flaming, with only a faint outline of human inside of a raging inferno.

Of course, I'm kinda opposed to overly sexualized non-human champions (so, pretty much your typical monster girls and shapeshifters (Elise, Zyra, Nidalee, ect.) so I'm sorry if I come across as overtly critical of your idea. The art is beautiful, no lie, and it is YOUR idea, it just strikes me like the the concept for an idea should be something different than just "(very) humanoid monster" like we have so many of already.