No description? - What's the intent? What's the purpose? What are you going for? Who is this dude? Looks like Cell from DBZ, on crack-cocaine.
Unless you're after "wow, koooool" responses, some explanatoriness, w/o that I don't know if you hit the bullseye on this or totally overshot and broke a window instead.
I really hate it when art needs an intent or purpose.
I mean a doodle is a doodle and a avatar is just an avatar, doesn't need a story behind it.
I think the helmet lacks volume, could be the orange going all the way across that makes it seem flat.
The face shows the volume that the helmet lacks.
Also the face is a bit messy a lot could be done to clean it up and use the colors better more on the highlighted side.
I don't know if the "poison bolt thing" is like shooting into his head or behind him.
Perhaps make more of a splash then like random spikes. or even just some spikes at the bottom, smaller ones.