Cool theme, man. Go for it
In my humble oppinion the demonic lavapattern looked the best when it was only shown on the lower legs and hooves. I guess I am thinking variation is your friend, both in color and in pattern. It's far from done yet I know but something to keep in mind and be observant about. Also keep in mind that it'd be my personal preferrence. Not necessarily yours. It's the latter that matter.
The uv's layed out so far, wow. Looks very clean and easy to paint on. I wish I could do that, but working on it.