In my DCU Doomsday would be an event not the name of the alien and it would be the most destructive event in my DCU. The story would begin much the same as the death of Superman with the creature digging his way to the surface and beginning has rampage. The first hero the creature would encounter would be Hal Jordan who would be killed by the creature. Hal's ring would then go and choose Kyle Rayner to be his successor. Upon receiving the news of Hal's death John and Guy would head to earth to also face the creature. When the Guardians view the footage transmitted by Hal's ring before his death they recognize the creature and order all Green Lanterns to stay away from Earth (John and Guy ignore this order). Ganthet knowing full well what the creature is capable of would chose to leave his brothers and head to Earth himself to aid the heroes there. We next see the creature meeting Hawk & Dove (Hank & Don) he would kill Dove and badly injure Hawk in the fight. More and more of Earth's heroes would encounter the beast and fall at his hands. Red Robin, Superboy, and Wonder Girl would all fall next. Guy Gardner would foolishly challenge the beast and would also be killed as John Stewart arrives too late to stop him. As more of Earth's heroes arrive they make a plan to use all of the heavy hitters to battle the beast up close while heroes with energy based attacks would blast him from the sidelines. The creature would seem almost unstoppable to their attacks with almost no damage being done to him and any injury healing its self before their eyes. Ganthet would arrive and begin to attack the creature doing the most damage with his blast and then an assault from Superman, Mister Majestic, Icon, Zauriel, Wonder Woman, Captain Marvel, and Power Girl would finally make the beast fall. As soon as the beast drops to the ground Zauriel would cut off his head with his Flaming Sword and then plunge it through the top of its skull and the fire would consume the head. Immediately following the death of the creature Amanda Waller would order the Freedom Fighters (see how I would do it Freedom Fighters) to recover the remains and hand them over to the United States Government.