I'm very impressed! Your attention to detail, and expression in the characters is pulled of really well! You have a strong understanding of shape and what makes a strong pose, and there's a lot to look at and enjoy in this picture, which I gotta say compliments the feeling of a MOBA in general (I'm a bit of a DOTA 2 fan myself hehe). The background is strong, but you're right, there's a slight clash between the central characters and the environment. I'd recommend using a more painted feel with the background, with less solid lines, or as least lines that match the color of the organic object they're framing (IE grey lines around rocks, green lines around grass etc). That way this solid linework framing your characters will stand out more, and the background will feel more cohesive in itself. Great work, very impressive! :)