The "War of the Elements" theme reminded me of a DnD character of mine, so I decided to use that character as a jumping-off point but just make him like.... way way cooler. So, the inspiration is a druid or shaman type character, who serves as a messenger for and avatar of the Storm God, who wields a great power that is not quite his own.
As for visual reference though:
And my concept art:
I'll probably make changes to the concept once he's in 3D (not sure if those pants will work in many poses, for one thing), but I like this as a starting point, and I'm quite fond of the stormy color scheme. I tried to give him a lot of loose fabric and dangly bits to billow in the wind once he's posed.