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    33 "Arrow," "The Flash," "Supergirl," "Batwoman," And "Legends Of Tomorrow" Details You Need To Know Before The Crossover

    "So, this is kind of becoming an annual thing, huh?"

    With Arrow, The Flash, Supergirl, Legends of Tomorrow, and Batwoman spanning almost ten years, the DC television universe is about to close a monumental chapter when "Crisis on Infinite Earths" begins this weekend.

    Basically, it's the DCTV crossover equivalent of Avengers: Infinity War and Avengers: Endgame.

    So, because this is such a massive event, below are some of the important moments and details you need to know before "Crisis on Infinite Earths":

    Obviously MAJOR spoilers ahead for Arrow, The Flash, Supergirl, Legends of Tomorrow, and Batwoman.

    1. First, the multiverse exists in the Arrowverse, which basically means that there isn't just one Earth, but actually hundreds.

    2. Green Arrow, The Flash, Batwoman, and the Legends of Tomorrow teams exist on Earth-1, while Supergirl and Superman are on Earth-38.

    3. In The Flash pilot episode, we saw a newspaper article from 2024 detailing The Flash's disappearance in a mysterious crisis.

    4. In the 2018 crossover "Elseworlds," The Monitor aka Mar Novu first appeared when he gave the Book of Destiny to John Deegan, who rewrote reality.

    5. In "Elseworlds," Oliver met with The Monitor and made a deal in order to save Barry and Kara from dying.

    6. Also in "Elseworlds," we were introduced to Kate Kane aka Batwoman for the first time.

    7. In the final moments of "Elseworlds," one of John Deegan's cellmates revealed that the universe will never be the same — in the comics, Roger Hayden aka Psycho-Pirate played a significant role in "Crisis on Infinite Earths."

    8. In the Arrow Season 7 finale, The Monitor returned to cash in on the favor Oliver owed him.

    9. The Monitor has seen the future and Oliver will die during "Crisis," and in order to protect Felicity and their daughter Mia, Oliver must leave them behind.

    10. Also, during the Arrow Season 7 finale, in 2040, Felicity reunited with The Monitor and was presumably taken to see some version of Oliver — we're still unclear on what this means.

    11. In The Flash Season 5 finale, the events from the newspaper article changed from 2024 to 2019 — Barry and Iris' daughter from the future ended up changing the timeline.

    12. Also, the newspaper article now mentions Batwoman, a recent addition to the DCTV universe.

    13. In the Supergirl Season 4 finale, The Monitor brought J'onn J'onzz's brother to Earth and resurrected Lex Luthor after he was killed.

    14. In the Legends of Tomorrow Season 4 finale, The Monitor appeared in the crowd when the Legends were performing in a superhero show.

    15. Now, in the current season of The Flash, Barry and Iris learned that the date Barry disappears on has been moved up to December 2019, and he will ultimately die.

    16. In Arrow, Oliver's first task after going with The Monitor was to travel to Earth-2, where he saw versions of Tommy, Moira, Malcolm, and Adrian.

    17. Also, Earth-2 was eventually destroyed by the same wave of energy that will ultimately destroy every world if The Monitor and Oliver fail.

    18. In The Flash, Barry went and saw Jay Garrick, so he could show him what exactly happens during the upcoming "Crisis on Infinite Earths" — the only timeline where everyone survives is if The Flash dies.

    19. Also in The Flash, Barry and Iris told the team of Barry's upcoming death and that it is inevitable.

    20. In Arrow, Oliver reunited with Thea to try and figure out more about The Monitor's motivations.

    21. Also, The Monitor transported Oliver and Felicity's children, Mia and William, and Diggle's son, Connor, to present day as part of his grand plan to stop "Crisis."

    22. In The Flash, another Harrison Wells doppelgänger, Nash, appeared on Earth-1 and has been trying to track down The Monitor.

    23. In Arrow, after The Monitor tried to get her to turn on Oliver, Laurel revealed to Diggle and Oliver that Lyla has secretly been working with The Monitor for a long time.

    24. In The Flash, Barry was infected by Ramsey's metahuman cells because he learned that Ramsey's powers could possibly save him from dying during Crisis.

    25. In Arrow, Laurel and Oliver were trapped in a time loop caused by The Monitor and Lyla, and they were forced to make peace with Quentin's death.

    26. Also in Arrow, Oliver finally accepted the fact that he will be dying soon, and he can't change his destiny.

    27. In Supergirl, we finally see where The Monitor has been keeping Lex Luthor, and that it's time for Lex to play a role in everything.

    28. In The Flash, Team Flash rid Barry's system of Ramsey's cells and he returned to being himself.

    29. Also in The Flash, Barry, Iris, and the team braced for the immediate impact of Crisis.

    30. In Arrow, Oliver, Diggle, Mia, Lyla, and the rest of Team Arrow were sent to Lian Yu in order to build a weapon for The Monitor.

    31. Also, Lyla revealed that The Monitor saved her years ago while she was stationed in Afghanistan — Lyla ultimately fulfills her purpose and becomes Harbinger.

    32. In Arrow, Oliver said goodbye to Mia and the impending Crisis officially arrived.

    33. And finally, during the latest episodes of Arrow, The Flash, Supergirl, and Batwoman, Nash Wells unleashed something, which will start the Crisis.

    "Crisis on Infinite Earths" begins Dec. 8 with Supergirl at 8/7c on The CW.

    The crossover continues with Batwoman on Dec. 9, The Flash on Dec. 10, and finishes with Legends of Tomorrow and Arrow on Jan. 14.