A gallery needs 3 pictures, so I recommend you add 2 more do you not want this one to get closed.
But, that's not the reason I comment. I like the take you have on Hydreigon, but I wouldn't call it semi-realistic. It's certainly a bit more detailed, and grittier, but I don't think it's a 'realistic' interpretation. I really like what you have done with the scales on its face, and his left hand has an awesome pose. One thing I do notice is that proportions seem to be a problem. The left arm seems thinner than the right arm, more so than perspective would allow, although with this dark background it may be the way the black blends over? The legs are also a bit awkward, as they look a bit too human, I feel. They look like they have knees, and feet will be attached, instead of being those weird tail like things that Hydreigon has. It definitely has a lot of potential though!