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This is a list of episodes which involve characters or plotlines from multiple shows in the Arrowverse. Since Arrow is the primary show and most crossovers involve characters from Arrow, they are arranged chronologically based on the Arrow timeline. The series in parentheses after each episode title list the show the episode is from first, then the shows from which other characters appear. There is then a brief plot description, covering just the basic interactions between crossover characters.
Oliver Queen, Felicity Smoak and John Diggle head to Central City looking for the boomerang killer, and help Team Flash fight Roy Bivolo, a meta-human who can cause uncontrollable rage in others. Oliver and Barry's differing methods cause tension between the two, and they are forced to fight when Bivolo uses his powers on Barry.
Cisco Ramon uses Felicity Smoak's facial recognition software to look for meta-humans outside Central City and finds evidence of Mari McCabe using her animal powers against thugs in Detroit. He nicknames her "Vixen" and gives her whereabouts to Barry Allen, who decides to take backup; he and the Arrow show up at Mari's apartment. When Barry uses her name, she panics and runs away. Flash and the Arrow chase Mari, who uses various animal powers to evade them, including speed, wall-climbing, camouflage and flight. They eventually talk; Mari explains she was not in Central City for the particle accelerator explosion, a fact confirmed by Felicity Smoak, and refuses their offer of help, threatening them with violence if they return. Flash and the Arrow visit Mari again, offering to help train her if she intends to become a vigilante; she says she is, but wants to work things out on her own. She asks about getting a codename and Barry says they call her "Vixen"; he lets slip Cisco's name, giving her a clue as to his identity. (Takes place around the same time as "The Offer").)
Cisco Ramon helps Team Arrow and Ray Palmer defeat the meta-human Jake Simmons, aka "Deathbolt", who has come to Starling City thinking no-one can stop him with the Arrow gone. Simmons is imprisoned in the Pipeline, but Cisco and Ray realise he was in Opal City during the dark matter wave, making the source of his abilities a mystery.
Cisco Ramon and Joe West head to Starling City to investigate the real identity of Harrison Wells with the help of Quentin Lance. Cisco also meets Laurel Lance and upgrades her sonic device, renaming it the "Canary Cry".
Barry Allen decides to move the meta-humans from the Pipeline at S.T.A.R. Labs to the A.R.G.U.S. prison on Lian Yu, to protect them from the plans of the Reverse Flash. He enlists the help of Leonard Snart, but Snart double-crosses the Flash and frees most of the villains. Barry then fights the Reverse Flash, defeating him with the help of Oliver Queen and Firestorm.
In a flash-forward to six months in the future, Barry Allen visits Oliver Queen in a graveyard, apologising for missing a funeral. Oliver vows to kill "him", and asks Barry to leave before weeping over the grave.
Team Arrow and Team Flash work together to save Kendra Saunders and Carter Hall from Vandal Savage, who is willing to destroy both Centraland Star Cities in his quest to kill them. They enlist the help of Malcolm Merlyn, who secretly recovers Savage's remains after he is turned to ash in the final conflict.
Approached by Rip Hunter to be part of his time-travelling team, Ray Palmer seeks Oliver Queen's advice, and decides to join. Sara Lance, given the same offer, spars with her sister Laurel, who encourages her to go and be a hero. She gives Sara a new codename, "White Canary", and a new suit to go with it that doesn't include a mask. Martin Stein, Jefferson Jackson, Kendra Saunders, Carter Hall, Leonard Snart and Mick Rory are also recruited, all in order to stop Vandal Savage from conquering the world in the year 2166. They travel back in time to 1975 to meet Dr. Aldus Boardman, an expert on Savage, whose information would later help Team Arrow and Team Flash defeat Savage in 2015.
At their first encounter with Vandal Savage in 1975 Norway, Rip Hunter's team find him selling a nuclear warhead at an illegal arms auction; one of the bidders is Damien Darhk, looking the same as he does in 2015, backed up by H.I.V.E. "ghosts".
Barry visits Oliver at Laurel's grave, apologising for missing her funeral due to Zoom. Oliver vows to kill Damien Darhk in revenge, and asks Barry to leave before weeping over Laurel's grave. (This is the flash forward scene from "Green Arrow".)
Rip brings the team back to Central City in 2016 - but five months after they left. Sara returns to Star City, where her father tells her of Laurel's death. Rip tells Sara they can't go back in time to save her. Sara and Quentin visit Laurel's Grave where Sara reveals it was Laurel that convinced her to join Rip's team, and she will continue for her sister. Meanwhile Professor Stein reunites briefly with his wife Clarissa,