First off it's a fucking beautiful piece. 448 faves at the moment so you can see it's a nice piece. Looking at it earlier, the details are all there and there's softness too in areas which really makes it beautiful. I think it can be a much better example of card art though. Looking at it on my phone enphasizes the issue to me. Most of my attention is either at the bottom of the image where the most red is or on the bright white spot on the left. I think the focal point of the tower is too low contrast/too small for the viewing size. It seems to me that card ADs often prefer bold and super dramatic compositions. So I would try to punch up that tower so it grabs more attention. That could mean more lava there or just more red such as the tower being red. If there's a pool of lava below the tower maybe that could cast a red glow onto the mountain the tower is on. Ut that would mean the ground being flatter and trees would probably be needed to hide the light source. This is real nitpicky and I mean super nitpicky but the tip of that mountain is a bit too symmetrical in terms of contrast for me. The left side is like a value of 7 against a 5 and the right side is like a 9 against that 7 so the difference in values is pretty close. I think it will take some playing to figure out if it's lightening the mountain on the left(if so I would darken the lit snow on the edge of the image on the left),lightening the sky for a streak on the right of the mountain or lightening the mountain on the left and darkening the sky on the right (to create a lost edge) along with maybe kicking up the glow on the lava to be cast out onto that darker bit of sky behind it. Anyways, I hope this is of some help for targeting that specific kind of work.