Hey there. That looks pretty cool. The first thing you need to do is fill in the entire frame. You also should clarify what the form is coming out of him. It looks KIND OF like his arm is outstretched with his hand out and hes like " oh no you didnt". If thats his hand, youll wanna clarify that.
For atmosphere...go fog crazy! Envelop him in fog and make the parts in shadow blurry. Make the parts further away blurry. Viola. Make sure you use a separate layer for fog because you'll wanna change it a few times--I always do.