The Best Episodes Written By Andrew Kreisberg

Pete and Myka race to stop Sykes from using his own cache of artifacts to destroy them and the Warehouse.

Andy is first pressured to go to Kevin's parent/teacher conferences, then is pressured to join the PTA by Toby's mother. During the whole ordeal, Andy has the hots for Kevin's teacher.

Oliver and Diggle race to stop the Dark Archer from unleashing his vengeance on The Glades. However, they run into a roadblock after Detective Lance picks up Felicity for questioning. Tommy and Oliver's already tumultuous relationship takes a turn for the worse after Oliver makes a confession about Laurel. After hearing of the danger in The Glades, Thea races to find Roy, inadvertently putting herself directly in the line of fire for Malcolm's devious plan. On the island, Oliver, Slade and Shado are locked in a life-or-death struggle against Fyers as his missiles lock on a full Ferris Air jetliner.

Wells presents Barry with a life-changing choice. Dr. Martin Stein and Ronnie Raymond return to help the S.T.A.R. Labs team with this final fight.

After covering from a near-fatal drug overdose, Oliver begins hallucinating people from his past. Believing he's a liability, Oliver gives the information he has on Cyrus Gold to Quentin... which results in the deaths of several police officers. Meanwhile, Brother Blood captures Roy and uses him as a test subject for his new serum. In the past on the island, Ivo gives Oliver an impossible choice to make.

As Oliver's face off with Slade escalates, his resolve to the no-kill rule is tested. Especially as Slade targets the woman Oliver loves.

A crossover event that began on "The Flash" concludes with Oliver teaming with the Flash to stop a boomerang-wielding killer who plants five bombs in the city that are set to explode at the same time.

With only 24 hours left until Savitar murders Iris, Barry struggles to save the woman he loves and makes the choice to use any means necessary to do so. Realizing he has one option left to save her, The Flash turns to Captain Cold for help.

Name partner Edwin Poole returns from a mental institution to Crane, Poole and Schmidt, ready to jump back in, but Shirley has reservations when he decides to sue a candy company. An A.D.A. with a grudge against Alan brings charges, accusing him of advising his client to flee when a guilty verdict was inevitable. Meanwhile, Brad and Denise decide where to take their relationship.

When Oliver and his team destroy Slade's centrifuge, he attacks them as Deathstroke to get what he needs to find a replacement. Meanwhile, Laurel ponders what to do with Slade's information, and Oliver tries to convince Thea to help him protect their finances from Isabel.

When a superhumanly strong thief robs a Queen Consolidated warehouse, Central City police scientist Barry Allen comes to Starling City to investigate the case. However, despite his close working relationship with Felicity, Oliver suspects that there's more to the young scientist than meets the eye. Meanwhile, Sin asks Roy to help investigate the disappearance of a friend. In the past, Oliver, Shado, and Sara try to get Slade to the submarine so they can use the serum to save his life.

Barry is thrilled when Oliver, Felicity and Diggle come to Central City to investigate a case involving a deadly boomerang. The crossover continues on Arrow S03E08 The Brave and the Bold.

Vandal Savage arrives in Central City and sets his sights on Kendra Saunders. After Vandal attacks Kendra and Cisco, they turn to Barry for help. Realizing how dangerous Vandal is, Barry takes Kendra to Star City and asks Oliver and team to hide her until he can figure out how to stop Vandal. However, things quickly go from bad to worse when a man with wings AKA Hawkman shows up and flies off with Kendra. Meanwhile, Harrison develops a serum to make Barry run faster and asks Jay to test it out. The crossover continues on Arrow S04E08 Legends of Yesterday (II).

Medical supplies are desperately needed for a crucial Republic battlefront. While the Jedi Knights transport Poggle the Lesser as a prisoner to Coruscant, the Padawans Barriss Offee and Ahsoka Tano are dispatched to escort the medical frigate to its destination. When Geonosian brain worms take control of the clone troopers aboard their supply ship, Ahsoka and Barriss must battle to stop the vessel from unleashing the deadly plague upon the galaxy.

While Artie and Claudia meet with Vanessa Calder and Hugo Miller to investigate a computer virus that transforms people into clay, Myka and Pete wake up naked in bed and try to find a missing Steve.

Shirley once again helps Professor Cabot, whose research into human sexual behavior gets him into trouble when he's caught with a prostitute. Marlene and Denise continue their fight for the spot to become partner by trying to assist. Meanwhile, Denny takes Alan to LA when he pays a visit to the West Coast branch of Crane, Poole & Schmidt, but his motives become clear once Alan meets Barry Goal. And Brad is shocked to discover his niece is arrested for participating in a drug "pharming" party.

When a villain calling himself the Trickster runs rampant in Central City, Joe and Barry go to Iron Heights to talk with the original Trickster.

The League aid the Justice Guild against their arch-nemeses while trying to unravel the secrets of the Guild's world.

Barry, Wells and Cisco journey to Earth-2 to rescue Wells’ daughter, Jesse from Zoom. Barry is stunned when he runs into Earth-2 Iris and Joe, but nothing prepares him for meeting Killer Frost and Deathstorm. Meanwhile, back on Earth-1, Jay has to take over the Flash’s responsibilities when a meta-human nicknamed Geomancer attacks Central City.

Diggle and Felicity travel to the island of Lian Yu in search of Oliver, who left Starling City after the devastation of The Undertaking and his failure to avert it. Convinced to return home, Oliver finds that things are in much worse shape than he imagined – Isabel Rochev is preparing a hostile takeover of Queen Consolidated, Thea refuses to visit Moira in jail, Roy is trying to fill the void left by the Arrow's absence, and Laurel is working with the District Attorney's office to take down the vigilante. Meanwhile, flashbacks to the island show Oliver's mentors Slade, Shado and Oliver in a desperate situation.

After Oliver is shot, he turns to a surprising person for help - Felicity. Diggle is stunned when he sees Felicity walk through the front door of the lair dragging a dying Oliver behind her, and the two team up to save Oliver's life. As Oliver hovers between life and death, he flashes back to a seminal event on the island - a daring escape attempt with his new friend Slade Wilson.

While training with Barry, Wally starts to have visions of Savitar, which he hides from the team. A dangerous secret threatens Barry and Iris’ happiness.

Oliver discovers that after he and his father went missing, Moira and Thea stopped celebrating Christmas. Determined to make up for lost time and restore a sense of normalcy to the Queen household, Oliver decides to throw the family a Christmas party. Meanwhile, Tommy asks Laurel to spend Christmas with him but she points out that Christmas was also her sister Sara's birthday and she needs to be with her father. Tommy suggests changing things up might be the best way for everyone to heal but Laurel isn't sure her father is ready for that. Meanwhile, Diggle tells Oliver someone is murdering the people on his father's list with arrows, which sends Oliver off to face his toughest adversary yet.

When aliens called the Dominators attack Central City, Barry speeds over to Star City to ask the Green Arrow for help in stopping them. Realizing the battle against the Dominators is bigger than they thought, they track down the Legends of Tomorrow, and Barry and Cisco create a breach to bring back a secret weapon – Supergirl. Once all of the super friends are assembled, they come up with a plan to attack but a shocking secret related to Flashpoint is revealed and suddenly no one is sure who they can trust. Meanwhile, Wally wants to join the battle against the aliens but Iris tells him he’s not ready. The crossover starts on Supergirl S02E08 Medusa (I). It continues on Arrow S05E08 Invasion! (III) and DC's Legends of Tomorrow S02E07 Invasion! (IV).

After Zoom unleashes an army of Earth-2 meta-humans on Central City, Barry is shaken when he sees their leader is the Black Canary’s Earth-2 doppelganger, the Black Siren. Meanwhile, Wally takes to the streets to help The Flash stop the meta-humans, which worries Joe. Iris and Henry are concerned about Barry taking on Zoom.