I love this I love to illustate scenes in my OC fiction too

Now this is a very dynamic piece! The color palette is very appealing as it has a sinister tone to it that goes especially well with the name of this picture.
The clouds look really heavy in the front and lighter in the back, which I think is a good thing.

I like the grass vey much It has realistic texture and shows where he beams of light that get past the clouds hit the ground! I wish he same applied to he mountains, because while they don't look bad or poor to me at all, they are a little srange-looking to me. It's probably that the ones closer to us have a lot of contrast but it doesn't do much to bring out their shape and I don't think it shows where the light is coming from that well. But after saying that I also have to say I think their shape and rocky nature are well done here, despithe blotchy light areas.

It looks like the two are fighting in a steppe, which I think is a nice choice for environment. It's also very interesting, because the mountains seem like they're everywhere around a wide, somewhat empy place where these two are just beginning an epic battle...
Faye's pose is really good. He's diving down, ready to atack Lucas, with on sword ready and the other waiting! His hair and clothes show movement, and he has a stern, focused face. And I like his clohes! Really, my only issue with him is that his wings look awfully thin where they start. I'm not very knowledgeable when it comes to the anatomy of wings, though. I suggest you have a look at how birds' wings look when spread out, and what the muscles and bones look like.
Lucas' staff is awesome. The gear-design and wooden staff are boh appealing details to me I like his clothes a lot as well (brown and white look good together) and I don't really have any issues with his pose, either.

Now, what I would like to point out about both of them is that I find your use of outlines a little odd. Faye's boots, for example, appear to have black outlines while his skin apparently doesn't. I'd personally prefer it if you stuck to a "red string" with them, as in all outlines of a certain color, or all outlines in suiable colors, or no outlines at all. Finding a balance can be tricky, though, and this is just a personal opinion.
One oher thing is that Faye and Lucas are not actually facing each other nor looking at each other, which kind of distracts from the fact that they're about to fight. Especially because Lucas looks like he's closer to use than Faye, but maybe it's just my imagination.
And this last point is not really related to the drawing, but I think it's a shame that there's a lot of deal that can't be seen in he fullview! And the downloaded picture fills up my entire screen and I have to scroll to even find the characters. Yet I don't think this picture would work if there wasn't that much background shown.

So, um, I hope I could be of some help!
And please ask me if I was unclear or if you'd like additional opinions from me on this piece.
Also, my keyboard is a little worn-out and T isn't working right So my comment may lack a few T letters here and there

Cool I didn't think this kinda' thing was your style.
I. Was. Wrong. It's epic

Actually, this is pretty good, Mango. Two things:

1. The blonde guy doesn't seem to be actually looking at the winged guy. His face should probably be in a profile view.
2. The mountains are the same color and value as the blonde guy's clothing, making it difficult to read his pose. I would lighten the mountains.

Keep up the good work!