My main account's king has always been themed around fire, and while there's an okay amount of bg's to satisfy me, the types of fire-related decor is a bit lacking.
There's the hellfire eyes, which I use adamantly, but I find the rest (hellfire decor, demon set) to be a bit too blocky and jarring.

What I'd like to suggest is something like magma dripping from the mouth, or little fire imps/demons that cling to the lion's body (but not too much) and also hang out on the ground. Maybe even a magma foreground that makes your lion appear to be standing in a pool of magma? Also the nightmare from the October event or hot scorching meteors falling from the sky behind the lion would be A+ as well.
edit: Heated chains, to the point they're glowing hot, would be great. Either some that drape over the main body or cuffs & chains on the legs that glow around the parts closest to the legs as if the lion itself is heating them.
Best example I can come up with- Fyrus from Twilight Princess

More ideas suggested:
-Stolen torch (held in mouth possibly?)
-Small flaming shrub decor
-Something like the windy decor but with fire sparks/small embers
-Flaming foreground
-Embers on the ground around the lion's feet/body, as if a campfire had just been put out.
-Human campfire, (to the left or right of the lion) im not sure exactly how this would look as campfires are done in so many different ways.

Possible bgs?
-A bg of an active volcano in Africa, like Erta-ale Erta-ale 2
-A fiery bg with fire tornado phenomenon