Superman's Motherbox creates a boomtube for him and Waverider to take to Calaton, where Desaad has sent Doomsday.
Upon arriving as Doomsday destroys the Radiant, it's clear that the monster has already killed hundreds and caused immeasurable damage.
As the Man of Steel battles Doomsday once again it becomes clear that he cannot win. Using the bracelet of the now downed Waverider, Superman has Motherbox take him and Doomsday to the end of time. There they find a recooperated Waverider who helps push the monster into entropy, where all life and energy are drained away to nothingness.
Doomsday is finally gone forever.