Are you taking about Phantom Zone Child Luthor?
If you indeed are, this fight is a draw. Remember this Luthor though his power affected the Multiverse, for he stop Death of the Endless from doing her job because of the aura he was giving off. He himself cannot attack. For the second he even thinks of a negative thought, the power would leave.
Beyonder would be unable to attack because of the Zone Child’s aura.