The Doomsday Rex is a genetic aberration designed to be an invincible predatory dinosaur, a life form that evolves and adapts.
It begins as an entity with tentacles and several mutated heads of Tyrannosaurus rex, although it seems to have DNA from other theropods such as Giganotosaurus or Allosaurus, in addition to DNA from octopus and marine creatures since it seems to have tentacles and various types of sensory organs exposed in its multiple skulls.
Initial form of the Doomsday Rex. Only the central head has eyes Its final form is that of a T-Rex with two heads and 4 arms, its vertebral columns are unified in the tail, but each head has its features, while the mutated heads seem to be blind since they do not have visible eyes, they could have several sensory organs, while the central head and the two heads of its final form have eyes, although these lack pupils giving it a demonic appearance.
Its size is enormous, surpassing the "Super Tyrannosaurus" that is seen in the concept art that is about 12 meters high, which exceeds any known theropod and is 3 to 5 times larger than the average height of a giant theropod that has existed. That means that its height would be more than 80 meters and its length of at least 150 meters
The powers and abilities of this hybrid are unknown since there are only a couple of conceptual arts of this creature from the canceled series of The Lost World: Jurassic Park.