DC Comics has given readers the biggest events in comics. These multiverse shattering - or multiverse rebuilding - events often revolve secret of some kind, one that the heroes have to figure out before it's too late. These secrets have taken many forms over the years, from hidden foes to truths about the history of the multiverse that no one knew about. These secrets have tested the greatest heroes, showing them that all the power in the multiverse can't save the day.
Source:https://www.cbr.com/dc-comics-biggest-secrets-doomed-universe/