Icon is good, much better to draw it than to screenshot trace it, but it lacks in some areas. You use style that is quite different from how blizz icons look like. You have an interesting approach with striking appearance, however since goal is to blend icons with existing game material I'd advise to go after archiving blizz feeling. And I'm viewing from that stance.
So, head is stylized in great amount. Since you chose this face position he should be more/less symmetrical. Space between eyebrows and eyes is unnecessarily large. Mustache aren't properly rendered and are too cartoonish. Face uses one color and two shades of it, which is fine, but kinda dull in overall view at least in my opinion. Also appears quite flat. Colors scheme of other parts is ok, even though I don't fancy the background too much. Shading needs more work. You should also lower size of brush as lines are quite fat. As of right now I would probably rate it with 3 (which I won't cos I never rate anything).
Anyways, icon is good from artistic view, however this style would need alterations to get blizz feeling.