Simply amazing piece! Almost makes me wanna play the game!
What impresses me most with the image is the determinsm of the brushstrokes! The brush is soo smoth and you can almost feel all the little bumps, cracks and cranies on the skin and armor. Further, the level of detail and shadowing is top notch, and the fact that it's made in a traditional medium just blow me away. Yet another artistic decsion you've made which I really like is just to keep the "eyes" red and the rest in black and white. Let's your eyes wonder around the red spots and see your amazing brush work. Really nice.
To give you soome critique, I'm struggling to give you any but let's try :) The only thing I can think of really is that I'd wished you had played a bit with the contrast when you put it into the digital medium. For instance the mouth is just a bit brighter than the dark part in the middle of the headpiece, which I think should be the same or even a bit darker in the mouth? Perhaps you could also have given a few of the teeth the second once over as some of them are a bit thinn, perhaps due to smudging during the paiting process? However, these are really me nitpicking since the piece is awesome.
Great design, execution, composition, you name it. Great work :)