First of all, it looks really nice specially the background but i also like the design of the character (god of war 
).
In cases of composition i would take attention that the pillar on the left so it doesn't take too much attention. It also creates an symetrical balance, wich is kind of boring.
I didn't check the rule of thirds, but i think it works and the eyes are guided as well.
Now when you pay attention to the Values, then i think it will be an awesome piece.
