Monsters!

[Zadaben]

made a quick edit between classes, like eman said, you do need smoother lines (although this doesnt mean you cant keep his cool shape) and less complex shading when you're working at this resolution, II wasnt sure what the energy stuff around him was supposed to be, but whatever it is, it needs to be brighter or it wont stand out, that purple blended with the background. You're going to want to tr to have solid color clusters instead of tons of little individual pixels, I probably could have done better myself in that department but like I said Im rather pressed for time. Hopefully this helps, might reedit my edit later on.
His design is cool I like him.