4. The Justice League
DC's major summer Event was Trinity War, a six-part (eleven if you count the tie-ins) story arc that involved the three Justice Leagues: Justice League, Justice League of America, and Justice League Dark. The three groups teamed up to uncover the mystery of Pandora's Box, leading to outright conflict between them when, in a shocking twist, Superman appeared to murder Doctor Light! Trinity War played on the number 3 repeatedly through its story the three teams, the Trinity of Sin, and eventually the Trinity turned out to be the Crime Syndicate from Earth-3, as they made their debut in the New 52. After multiple superhero fights, the Event ended disappointingly with the arrival of the Crime Syndicate. Rather than give readers who'd been following along a proper ending, after the Crime Syndicate showed up, readers got a "To be continued in Forever Evil" tag on the final page. Reading Forever Evil #1, we discovered the Crime Syndicate had killed the Justice League, which is why they were able to carry out their plans unopposed. It was a pretty shocking revelation especially as it all happened off-page. One minute the Justice Leagues were facing the Crime Syndicate, the next the Crime Syndicate had taken over the world and were claiming to have killed the Justice League! Definitely not the most satisfying of deaths DC could've done. So are the Justice League really dead? Nope! As readers of Forever Evil will know, it was revealed they were captured within the Firestorm matrix and held in a superhero prison.