"Since you asked, I shall inform you Master, as to you wish for retaining of your intellect, this of itself can be a default for your future.
Your making a wish to become as an animal in bodily form, that is easy for magical spirit to arrange through evil forces. No Heaven bound spirit or Angel and above their place of honor would dare go against the will of the Almighty. So, as with dealing a contract through devils, to demons, to the higher achy in Hell, the request to transform a person to become as an animal is done through a curse.
Remember, I said it was an easy task, but Demons tell their devil subordinates to transform the cursed subject of body and mind. The primary reason the Demons would prefer your mind as made beastly. As that with you retaining your intellect, you might someday implore the Almighty to have pity and by repenting he will take pity, and redeem your soul.
The Demons do not make open end deals, and if they would agree to your terms, expect some manner of soul infecting of other by you, your touch, or through sexual contact!"
Hearing all of that causes Jared reasons enough to think further about what he implores the Medallion to do.