You can't actually define those demons, they look really ugly, because of their polygons. Either try to add a green tone (but retaining the black one), e.g. 0,50,0 in the RGB scale, since the terrain shares a green fog, or change the models.
The lighting looks a bit unnatural and blurry, but I guess it mixes well with the scenery.
The waterfall from the left doesn't even follow physics. It creates an angle upwards and then it falls = unnatural. The waterfall on the right side falls on the ground, but there is no water beneath it. Add some sort of pond. Use lower tool and add the Water Plane model from Ultimate Terraining Map.
Finally, add some trees in the background, it doesn't feel that mystical, when it's that empty.
P.S. Medivh isn't that stupid. Even though you make him look like he doesn't know what's behind him, I'm sure he has eyes on the back of his too
