Is the shaman multiheaded or is his head the ram skull? I'ts hard to tell. At first glance i thought the human skull was his head which looks a bit awkward, the brown scarf looking thing is running up the middle of the mass of his body leading to the human skull. easy fix might to give his eyes a glow so there's no doubt which head you want the focus on.. As for lighting I think he would be picking up a lot more orange and red light being so close to the fire, even the smoke which looks too evenly lit the whole way around his body. My guess looking at it, is that hes absorbing the fire from the lion. maybe if you separate his on fire hand from the line so it doesn't get mixed with the other flames might be good. Anatomy could use a bit more referencing/studies.
Well done sofar
Just a quick tip on composition. You have sliced your canvas down the middle which makes for a very dull composition. Play with moving the figures around, cropping etc to get something more dynamic. Also might want to think about adding depth between the shaman and the lion rather than on the same plane.