this is really cool,bro.
The main issue in my opinion is that huge dragon behind the castle...You kinda have 2 focal points,the dragon and the castle (this isn't a problem at all),but you didn't put them in a good composition.
The painting should look more great if this dragon wasn't too visible,know...His pose is kinda weird.I can't see where is he/how is his pose.
OR
you should make his head in a diferent way,or smaller.Just to set up the right focal point or to polish both of the focal points