to add to what lux said...
might want to make the front leg a bit wider at the bottom and bring it forward a bit... similar to what you did with the spear... also add a touch more shading and fine details... and your away
Perspective is quite the tricky little thing, but you did a good job with it here.
Bright colors bring it out and the character sets a mood. The character rings as a "dark hero hellbent on revenge" type. The mask makes him look evil, and the cape gives a mysterious or epic feel. His skin color is a tad strange, but that's mostly because it's color feels weird in conjunction with the color of his clothes.
The background looks nice; it's simple, as something in the distance and out of focus usually would be. The setting is cool, a craggy valley type area that makes me think of our hero crossing a wasteland for his mission.
You need to try and make your line-work cleaner, though! It's messy in a lot of areas. As well, the sky is a little plain.
As a whole, it's quite good!
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