What role does doomsday play in batman v superman?

Lex Luthor combines the remains of his own engineered being, known as the “Kryptonite Man,” with a sample of Superman’s blood and the alien technology of a crashed Kryptonian ship. This fusion resurrects the creature as Doomsday, a nearly indestructible monster. Doomsday emerges during the film’s climax, breaking free of a prison and rampaging through the city. His overwhelming power compels Batman, Superman, and Wonder Woman to set aside their differences and battle together. The fight ends with Superman sacrificing himself by using a kryptonite spear to stab Doomsday, causing both to die, which drives the narrative toward the formation of the Justice League.