At May Sweeps, the CW president Mark Pedowitz revealed teases about the biggest event Arrowverse fans are waiting for: “Crisis on Infinite Earth.” The crossover has become an annual event since “Supergirl” joined the CW and brings together heroes from four DC shows. The recent seasons' crossover event "Elseworlds" teased “Crisis on Infinite Earth” with the finales of “Arrow” and “The Flash” adding hints about what's to occur. The deal Oliver made came back in the "Arrow" finale, answering the biggest question about this season's flashforwards: the whereabouts of Oliver Queen.

The Monitor made his return, collecting Oliver on that deal and bringing Oliver to help with a mysterious mission. “The Flash” ended its season with a change in the timeline and an ending teasing Barry Allen's disappearance has moved up to 2019. “Supergirl” is expected to leave another “Crisis” clue in the finale on Sunday.

Oliver and Barry's possible 'Crisis' fate

Not much is known about the “Crisis” except the few teases dropped in the shows and from the CW president, but "Arrow" made it known that Oliver will possibly sacrifice himself to save the world as the Monitor told him the Crisis would claim his life. The ominous comment coupled with this upcoming season of “Arrow” being it's last, it's a safe bet Oliver could die in the Crisis.

The final season will contain only 10 episodes, which is about half of the number of episodes the show usually has so the crossover could be used as a way to send the show out with a bang. TV Guide reports tease from “Flash” EP Todd Helbing about the crossover containing answers to Barry's disappearance which will play a major factor.

Barry vanishing has been teased about for a while now as Nora came from the future to help prevent it but she lacked answers to what event caused him to vanish. At the end of the finale, a time flux changed the course of the future, not only erasing Nora but also moving up when Barry is meant to disappear.

A five-part event set for December and early 2020

This last crossover didn't feature “Legends of Tomorrow” who opted out and even made a couple of references since poking fun at their absence. Mark Pedowitz confirmed at Upfronts that “Legends” will, in fact, be apart of the big event though the show won't return for its fifth season until midseason 2020. This means the crossover will be split between five episodes with three airing in December and the other two early 2020 which will be when “Legends” airs. All five Arrowverse shows will take part in the big Crisis: “The Flash,” “Arrow,” “Legends,” “Supergirl,” and newcomer “Batwoman” who was first introduced in the “Elseworlds” crossover. Pedowitz describes the crossover as the biggest and most complicated one they've done yet.