Well, this will be my first critique. So let's get to it.
This picture has a very strong power. I like the warm color, and I like the pose from Scootaloo. I saw a lot of ponys closed as ninjas or assassin, mostly Rainbow Dash and Scootaloo. Maybe this depends on their character. But doesn't matter as long the drawing fits.
Your technique is truly one of the best from the pony-artits I know. With your style you made the art very energetic, what should I say? - Awesome!
You named the picture "Anger" it shows very much anger, the background makes the feeling even stronger. Without a doubt the right title, but not strong enough, there are stronger words than anger. As I see Scootaloo's going to explode in wrath!
So far enough! This is one of the best mlp artworks of this kind. Well done!