I know why you got turned down, but I still really like that you have worked for a client. I like the composition and perspective and the symbolism is great. I think it just lacks that extra bit of work (highlights, depth, shadows, layers, reflections are all there but needs to be more detailed) I also think you need to go for a higher contrast and deeper, wider palette. Really study the hex values (hues) that magic the gathering are using. The artists use loads of hues. I like it, but I am only giving an opinion that it does not look finished.
Hey~ Thanks for the advise, how to using the color is really a big field for me to explore and to learn. That's why recently I practice a lot of works to boost my experiences. I didn't go to art school until last year I changed my path to art graduate program, therefore, I know I have a lot of things need to catch up. But I enjoy this learning process : D, and I will keep your advise in mind ; )
p.s: I have to admit that I am still a little bit lazy in handling those details right now, but I am getting more and more patient to do that! Just need time to practice it. lol
Yep, I think that's one of the main reason. XDDD I though Selesnya needs powerful weapons to maintain their PEACE! lol Alright, no kidding. Anyway, I will draw another more peaceful centaur for them later.