Okay. Here we go.
The spikes should be of a lighter hue, and the edge of it really dark. (more contrast)
You want a clear image that instantly shows that these are scary spikes, so get rid of the other little things that are coming off the spike.
The glow around the icon isnt that good. Glows are usually for units, not spells. (I might be wrong, but this glow doesnt really fit.) If you can, I suggest some faint lines as a BG, to show the spikes are rising from the ground quickly.(this line thing might look weird, and If it does, just get rid of it, so use 2 or more layers)
Finally, if you can, you should put your image in a worms eye view, so the spikes look menacing. This also means you have to completely redo your icon, so its not recommended.
If you want to look at it. Not extremely useful.