Through black arts you have changed your fate. A sorcerer at the end of their life has bound their eternal essence to an emanation of creation.
Never ending! Immortal!
Grandiose as eternal life may be - transforming one's self into a Thorn Man, or an Imp as they're often called, means you are even less powerful than when you were a human. But, all things can be regained in time. And there is nothing you have more of now than time.
But there is one thing that needs to be done before anything else: To solidify your place in the universe, you must have a Name.
A True Name.
Choose wisely.