I will start with anatomy and design. First, without knowing anything about the inspiration for the piece, I really like this creature. The scales and the mouth all have a soft glow to them that reminds me of professional illustrations used for big-budget computer games. I also like the design of the scales and thorny spines, and you did a good job of showing the dimensionality of the scales and the fleshiness of the mouth's interior. Now, it seems like you are going more for a relief-carving style rather than fully realistic dimensionality, and if so, you do it well. However, the anatomy of the head isn't quite right; the area where the jaw hinges should show some folding of tissue and bulging of muscle under the skin as the dragon holds its mouth open. Knowing that this creature is derived from a snake in the viper family, some other problems are apparent. Firstly, the scales are very fish-like. Vipers have riged, often pointed scales, arranged in a very geometric pattern of overlapping where each scale sits precisely in the gap between the two behind it. Also, snakes' scales do not cast shadows over the scales in front of them, because they lay flat on top of each other under a layer of skin (the layer that is periodically shed). Another observation I would add is that a creature with such long, thin fangs sticking out the front of its mouth would run a big risk of breaking them; which isn't to say it couldn't work in theory, but just that you may want to re-consider either the position or the proportions of the fangs. I would also recommend looking at photos of vipers and their relatives to get a better idea of the anatomy of a snake's head, as there are some details you could add which would really make this creature's heritage clear. Additionally, I notice that two teeth on the upper jaw, and three on the lower, are shaped like dogs' molars rather than like snakes' teeth. You may want to change this. Snakes have small, regularly-spaced, similarly-sized teeth unlike crocodiles, and the teeth are all the same shape, unlike a mammal. You may be interested in looking at photos of snakes' mouths to see how their teeth and tongues look. Finally, snakes do not have eyelids but rather large, round eyes with a scale covering each, and they do not have facial muscles with which to squint or look angry; thus a dragon descended from a snake would probably have similar eyes rather than the squinting eye of your creature.

From a technique standpoint, I really have no criticism to offer. I think you had a clear idea of what you wanted to do, and you made it happen. Your use of red and green as the primary colors here with a neutral (black) background means your use of color is spot-on.

Overall, I like the idea behind this piece because, in Medieval and prior literature, the word "dragon" refers more or less to giant constrictor snakes, and so I like to see dragons whose designs are drawn from snakes rather than dinosaurs or birds. I also think a strong feeling of otherworldy aggression radiates from this creature-- as it should.