Hey TheSceriffo!
So the way it would work is using a post-process volume. You would apply a material in the post-process (In client ONLY so the one who casts the spell is the only one who sees), and the volume for the post process will be exclusively in your smoke cloud.
Check out this tutorial for tips. You’re probably going to do this 95% exactly how it details in the tutorial, you’ll just make the volume on the fly.