Might I suggest two things regarding the lava textures- one, lower the scale on the up close terrains and two, add a noisy texture to it (try a sand or rugged rock) to get some granularity. It is too smooth at the moment. I would also tweak your fog, it is too sharp a transition line. I think the motion blur is best done with appropriate masks in post work. Not everything should be blurred, hence the masking) Lots of promise. Give it another go!

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