After being regrown by Lex Luthor, Doomsday was genetically part-Kryptonian due to his genes having been spliced with Kal-El's. However, with the exception of his flame-breath, he displayed no additional abilities. In fact, he was shown to be weaker than previously when he was single-handedly beaten by Superman. This was attributed to intelligence that he developed, causing him to fear the death that awaited him if he lost, but did not explain how a simple minor concussion could incapacitate his healing factor for the time he remained unconscious. However, he apparently lost his intelligence when he was sent back in time, reverting him to his original state of fearlessness.