To be perfectly honest, I have little experience with this style of art. The only "big name" artist I know of who works in this style is Tim Burton. Nevertheless, I will endeavor to give you some useful criticism.
The compositional idea for this picture is sound. It suffers, I think, from the way the black border is cut off at the sides. This may have been intentional, but unfortunately, due to how close it comes to not being cut off, it looks accidental. This is something that you really want to avoid. Alternatively, if the top border seemed more tooth-like, I think that it would work as it is, because it would seem like a mouth. Border aside, the way you've made Siajh seem much more menacing and dominant both by virtue of his scale and looming position is very effective.
Black figures on a black background are always very tricky. I can see how you've resolved the clarity problem with the classic method of separating the figure from the background with a thin white border. I believe that your piece could be improved by making your white border either more visually interesting, or more integrated into the subject matter of your drawing. Perhaps your could give the impression of the figures being back lit, of having their own luminosity, or of being white paper cut outs placed on a black background, to list just a few methods. This [link] is a particularly pleasant example of a black on black drawing.
As to the anatomical and facial details of the figures, I don't really know much about this style, as I said, but their paleness, angularity and grotesque distortion really add an aspect of horror and fear to the image - I assume that was what you were going for.
Please let me know if you disagree with any of this, or just want further input on any specific area. I hope I was able to be helpful