Vision I do not know who is the character you portrait here, where is she from. So I can only comment for the concept of her; since she is the main theme of your artwork. The browns and red tones all on her, sparkles in her eyes give hints about her nature, which is a good accomplishment in this case. She might be evil, twisted twin sister of some fairy, or just a women after revenge of past events. She has angry and daring looks; narrowed her eyes a little bit. She is obviously up to something that is not good for her target. Enviroment also have clues about where she probably came from. It seems to me your artwork is about the character and you tell about your character quite well.
Originality As I have said; I do not know if she is an original character of a fan art. She is new to me. There is nothing in her design that I haven't seen before but I love the fact that if you remove the grudgy looks, she would look innocent and childish.
Technique Blurred distant background leaves the focus on the character which is what I would want in this artwork and it is well done. Painting her anatomy in a cartoonish style gives her the underlying innocence. And it makes the proportions nice to eye. Maybe you could work on her hands more. Burning rocks are good touches giving the picture depth. But I think it would look better if you had made their directions different with giving one of them a different angle. Also, it is so obvious that they are exactly the same rocks with same flames which is impossible in reality. Even if my eyes are worng and they are different; they look exactly the same. You could warp one of them a little, and mask different parts of the flames of one of them so they would look random and different rocks. Maybe you can add a little blur to the front edge of bigger rock to enhance the depth feeling. I see there is a global lighting that is ok, but also there is a red-yellow light coming from the bottom of her. So you can add some highlights to the certain edges of her. It would look better if you define the seperation line between her feet and legs.
Impact It definitely creates the impact of her anger towards to people looking at. You feel like you are the one who she is coming at. That point of view is the basic thing that makes this work good.
Deviousness In general, I like your work. Most importantly, in every part of it, I can see the glimpse of the quality you can get into your art in future. Obviously you have potential; all you need is make more art, and work long