I was gonna add something towards the black background but I wasn't really sure what would fit there and not interrupt everything else going on.

EDITED.

 

Inspired by this? Warchief Thrall

 

Yessir!

 

Can you upload bigger size image? Just interesting.

 

Here ya go.

 

Neat, thank you.

 

No prob!

 

The whitish trail is kinda overdone and unfitting with the slam effect in my opinion.
I also thought about adding a thin red trail for the red gem on the hammer, not sure if it will looks better though.
The yellowish highlight on the gem looks kind of weird too.
Hope you don't mind my blabbering, just telling what I sees.

 

I'll approve it, it is drawn nicely, but the color scheme could be better, consider changing it for the key elements to be more cohesive: gem, the effect, blue tracks across hammer. Also, aside from gem, image could be less desaturated.
Movement illustration could be connected more with the background rather than with foreground, like below example there is a light outline and movement effect appears to be attached behind the object:

This is important because you don't want to give too much focus on the effect, but to the main subject which is hammer itself. Both effects (movement effect and yellow effect) should be ''lower rank'' of importance compared to it, because otherwise image gets crowded with information that aren't contributing to overall illustration much. That's why it is better to keep ''add-ons'' away from foreground and if possible to keep them subtly merged into background.

 

Thank you sir!

 

A very nice, high quality icon. Can't fault it personally!

 

Looks great!

 

very good