Bathin is a Duke (Great Duke according to Pseudomonarchia Daemonum) of Hell, who has under his command thirty legions of demons. He knows the virtues of precious stones and herbs, and can bring men suddenly from one country to another. He helps one attain astral projection, and takes you where ever you want to go.
He is depicted as a strong man with the tail of a serpent, riding a pale horse.
I want to go for a medieval vibe on this one. Static, unnatural posing. A demon white horse covered in a blanket of herbs and flora. The demon (I will play around with his facial design) sat atop the horse sniffing a bouquet of herbs. Conjuring the form of a human face in his other hand.