Doomsday

Doomsday was created through the cloning of an infant and having it killed over and over again by one of the most dangerous species of the universe and in one of the harshest habitats in existence, prehistoric Krypton. As such, the infant evolves and returns to life, becoming resistant or immune to whatever killed it before. After the Radiant killed him the first time they fought, Doomsday grew immune to the former's energy-projection, and even managed to withstand Darkseid's full Omega-Effect.[5] The amount of damage dealt to Doomsday determines the length of time it would take to fully recover. During his outwardly undamaged death at Superman's hands, he only needed some days to recover, but when Imperiex reduced him to a skeleton, it would take months. His entombment in a Calatonian burial suit and metal vault lasted thousands of centuries: after being killed by the Radiant and subsequently undergoing the impact of the casket on Earth, his body was sealed underground in total darkness. Deprived of solar energy, he could only revive extremely slowly.

Doomsday can also develop/evolve resistance from ordinary injuries. Superman once used a sound gun to greatly discomfort him, but Doomsday's auditory canals closed up, making him impervious to Superman's weapon.[5] Waverider once paralyzed Doomsday with chronal energy, but the second attempt backfired.[5] In essence, Doomsday gradually turns more invulnerable if not injured beyond his ability to recover, which is so far undefined. Doomsday has also developed weapons and abilities that counters the powers of an opponent. He managed to cancel out the pure-energy Radiant by slamming into him; to greatly extend his claws and develop a poison to strike Superman in flight and reel him in;[5] or breathe flames against the fire-sensitive Martian Manhunter, and apparently neutralize his defensive phase-shifting power.[6] Doomsday's skeleton protrudes through his skin in razor-sharp spurs which provide protection to his few vital organs (brain, eyes, nervous system), and act as clawlike weapons on his hands, elbows and knees.

Doomsday possesses extreme physical strength that, variable as it is, sometimes exceeds that of Superman, at one point enabling him to effortlessly stand his ground against the entire Justice League, including Superman and Orion.[7] He was able to break Superman's left arm with limited effort, as well as outmatch and beat Darkseid unconscious in physical combat.[5] However, his strength has limits: the immensely strong Calatonian alloy cables, in which he was entombed, continued to partially restrain during his initial rampage on Earth. It was never stated how long he had struggled to free his left hand before his escape.

Doomsday is immensely resistant to heat, cold, and conventional damage, allowing him to survive on the most inhospitable worlds, or in the vacuum of space. His durability apparently also considerably exceeds that of Superman, as he was able to withstand Darkseid´s full-powered "Omega Effect" without any shown damage.[5]

Doomsday possesses seemingly inexhaustible stamina, and was not noticeably slowed down from fighting Superman for an entire day. His speed and agility are vastly disproportionate to his bulky stature, and has been able to match Superman in this regard. He cannot fly, but rather travels by leaping miles at a time. Superman took advantage of this in their first battle by trying to keep him airborne, as the sky was his element.

Doomsday has a highly accelerated healing factor that allows him to quickly regenerate from most damage. When his side was cut by Superman with a plasma sword, it closed within moments. As a result of his engineering, Doomsday does not need to eat, drink, breathe, or sleep, and his body is almost solid mass with few vulnerable organs.[5]

Doomsday is now genetically part-Kryptonian due to his genes having been spliced with Kal-El's, however with the exception of his flame-breath, he has displayed no additional abilities. In fact, he was shown weaker than previously when he was singlehandedly beaten by Superman, which should not have been possible given previous accounts. This was rationalized as due to intelligence that he developed, causing him to fear the death that awaited him if he lost, but does not explain how a simple minor concussion could incapacitate his healing-factor for the time he remained unconscious.[6] However, he lost his intelligence when sent back in time, reverting him to his original state of fearlessness.[citation needed]

Once he gained some of Superman's Kryptonian DNA, he became susceptible to Kryptonite. Unlike Superman, it causes him pain, but cannot kill him.[citation needed] This was done to render him controllable.