As Bloodwork prepares to unleash his final plan, Team Flash struggles to find a way to reach out to the newly-minted Dark Flash.
- Action Survivor: During Bloodwork's attack, Nash fights off the Blood Brothers underground, doing the best he can.
- Aesop Amnesia: It seems Cisco forgot the lesson he learned about making Betrayal Insurance to take a renegade Barry out in "Going Rogue" and "Mixed Signals".
- All Your Base Are Belong to Us: At the episode's climax, Ramsey leads his infected army in attacking S.T.A.R. Labs to gain access to the particle accelerator.
- And I Must Scream: Barry was completely aware of everything Bloodwork ever did while he was the Dark Flash.
- Assimilation Plot: Ramsey plans to use the Particle Accelerator for bringing everyone under his thrall, by spreading his essence.
- Assimilation Backfire: It turns out that Flash allowed Ramsey to infect him to manipulate him from the inside, followed by causing Ramsey to see a vision of his mother.
- Back-to-Back Badasses: Frost and Joe fighting off a bunch of zombies together, with Allegra coming to their assistance after Joe is injured.
- Bait-and-Switch: It initially seems that Rosso quoting things Barry said to Iris and Cisco is an intentional Kick the Dog moment. Actually it’s Barry Fighting from the Inside and sending a message.
- Batman Gambit: Barry let himself be infected by Ramsey so that he could manipulate him into a trap.
- Big Blackout: Ramsey's Zombie Apocalypse comes with a huge blackout affecting the entire city. This and cutting the phones was invoked to stoke fear in the populace.
- Bittersweet Ending: Central City is saved, but Crisis is imminent; the final scene of the episode is Team Flash counting down the last few minutes before it begins, reminiscing over the past few years.
- Bloodier and Gorier: Downplayed, but fitting with the episode's Resident Evil shout-outs, the blood spray from Joe's back wound and Bloodwork's final form feature a lot more blood and viscera than is typical for the series.
- Body Horror:
- The black blood seeps its way out of Barry's body to the point that it even affected his costume.
- Ramsey's grotesque transformation.
- Bond Villain Stupidity: Subverted; it seems Rosso is falling into this classic bad guy trap when he tells Cisco his plan only to let him go. Turns out it’s actually Barry Fighting from the Inside.
- Call-Back:
- The Dark Flash lures Iris into a trap by telling her through comms to meet him at where she accepted his wedding proposal, in their loft.
- In the denouement, the team reminisces on a few of the adventures they had over the years.
- Chekhov's Boomerang: The particle accelerator is an important element in the story once again, as Ramsey uses it to attempt to infect everyone in Central City, while Allegra's light makes the explosion revert Bloodwork's infection.
- Chekhov's Gun:
- The adjustments "Barry" was making on S.T.A.R. Labs' computer back in Part I was actually Bloodwork preparing the Particle Accelerator for his plans.
- The M.A.C., which was used to contain Chester's black hole particles, is used to contain Ramsey because the Pipeline’s cells weren’t strong enough to hold him, based on the encounter with Mitch Romero earlier in the season.
- Chekhov's Skill: Allegra’s ultraviolet powers are used to eradicate Bloodwork’s infection from his army.
- Cliffhanger: The episode ends with the skies turning red as the Crisis arrives.
- Conservation of Ninjutsu: Averted. Nash handles himself fairly well against one Blood Brother, but he's outmatched when more of them arrive.
- Crazy-Prepared: Cisco had a plan for S.T.A.R. Labs in case Barry went rogue, expanding on his first Babel Protocol (and even calling it Babel Protocol 2.0), where a force field would be put up around the building that even the Flash can't get through.
- Dark Messiah: Ramsey ups the rhetoric in this episode, describing his infection as his victims' salvation, claiming that "curing death" is his destiny, and justifying sparing Cisco by saying he wants him as a "messenger" to spread his infection far and wide.
- Deflector Shields: Cisco puts up a giant one to defend S.T.A.R. Labs, most likely an expanded version of the trap he originally built for the Reverse-Flash.
- Didn't Think This Through: Cisco thought that shooting Ramsey with his photon gun would be enough, but failed to foresee that someone possessed by Ramsey, including Barry, could thwart his plan.
- The Dragon: Rosso has converted Barry into one.
- "Eureka!" Moment:
- When Cecile mentions how filled with fear she is, Kamilla realizes that she's actually sensing the fear within the Blood Brothers, meaning that she can sense them and enable her and Kamila to escape.
- While Cisco and Iris discuss Ramsey's words, they discover that Barry was Fighting from the Inside trying to reach out to them and that he is saying that Allegra's powers are the key to stop the infecting blood.
- Evil Is Visceral: Bloodwork's final form is a hulking monster with a gory skull and red, pulsating flesh that resembles exposed muscle.
- Evil Makes You Ugly: Ramsey's final form is a large, crimson, pulsating abomination with a Skull for a Head.
- Femme Fatalons: Dark Flash grows sharp, dark claws.
- Fighting from the Inside: Barry is revealed to be doing this throughout the episode.
- Foreshadowing: For all his detachment and arrogance, the Monitor has never asked anyone, even those who work for him, to kneel before him or swear their allegiance. This, coupled with the fact that the Crisis begins within minutes of Nash submitting to this command, all but confirms that it wasn't really the Monitor Nash was speaking to.
- Hallucinations: Ramsey has one of his mother begging him to stop what he's doing, after Barry triggers his repressed doubts about his plans.
- Hive Mind: Ramsey and his blood army. He can even speak through them.
- Hoist by His Own Petard: Barry uses the Psychic Link created by Ramsey's infection to get into his head and stir up his doubts about what he's doing, which distracts him long enough for Barry to grab him and toss him into the M.A.C.
- Hope Bringer: Cecile calls Barry this, quoting the late H.R. Wells.
- Hope Spot: The photon emitter actually works on Bloodwork just as Cisco intended, until the Dark Flash knocks it out of his hands and destroys it.
- Hypocrite: Ramsey is sincere in trying to use his powers to save everyone from death. But then he decided to kill those that resist him anyway...
- "I Know You're in There Somewhere" Fight:
- Iris initially tries to have Barry win control on his body, but fails. However, Barry's plan actually depended on him not returning to normal right then, so who knows what was actually going on in the Dark Flash's head at the time...
- Ramsey's vision of his mother, formed from his own inner doubts, tries. Flash wisely doesn't give him time to make up his mind, whisking him to a Tailor-Made Prison while he was distracted. In the end, Ramsey returns to his usual madness, having learned nothing, and it's not down to a grudge about that, either.
- Ignored Epiphany: Ramsey's vision of his mother seems to awaken his inner doubts, but as soon as he's locked up in the M.A.C., he's back to ranting about saving people and his own destiny.
- Irony: Frost chokes once again and forcibly turns back into Caitlin so she could treat Joe's injuries. Caitlin had to summon her back because she points out that Frost's powers are needed for the operation anyway.
- Just Between You and Me: Ramsey outlines his plan to use S.T.A.R. Labs' particle accelerator to spread his infection to all of Central City at once to Cisco. This is mostly because he's being influenced by Barry, to make Cisco realize what Barry's plan is.
- Kick the Dog: For all of his rhetoric, Ramsey obviously enjoys messing with Barry's friends through him.
- Kneel Before Zod: What the Monitor (at least, someone that Nash assumes to be the Monitor) demands Nash to do. The Stinger shows Nash accepting, triggering the Crisis.
- Knight Templar: Ramsey honestly believes himself to be a hero.
- Last Villain Stand: With Barry and everyone else freed from his control, Bloodwork flees and attempts to start over, only for Barry to confront him for a Final Battle.
- Leeroy Jenkins: Iris insists on going to her loft to try to awaken Barry despite being risky and jumps to stop her. She barely survives because of Barry's small control in Ramsey's mind.
- Manipulative Bastard: Ramsey uses Barry's memories and voice to try and get close to Iris so he can infect or kill her. Barry Fighting from the Inside is the only reason it doesn't work.
- Mythology Gag:
- Iris almost suffers the same fate of her comics counterpart Pre-Crisis. The difference is that Barry prepares to stab her through the heart instead of through the head.
- Ramsey adopts his supervillain look in live action.
- Cisco’s Babel Protocol returns, again a reference to Batman’s Betrayal Insurance in the memorable JLA: Tower of Babel arc.
- Nice Job Breaking It, Hero: Nash Wells inadvertently begins the Crisis in The Stinger.
- Offscreen Moment of Awesome: In two different battles, Frost and Joe, and Nash fend off Ramsey's thralls. They would then cut to different scenes, but when it cut back to them they were actually fending them off for a while now. At least until Joe gets injured.
- Offscreen Teleportation: While everyone is distracted by Barry coming back to his senses, Ramsey flees without being noticed.
- Once More, with Clarity: We finally know why Nash is touching those symbols. He thinks he finally has access to Mar Novu's realm (actually the Anti-Monitor's, unknown to him) and that Mar Novu saved him from the Bloodwork!zombies (actually Allegra's light), so he agrees to submit to not!The Monitor and... triggers the Crisis by freeing him.
- The Oner: There is a roughly two-minute long, mostly uninterrupted camera take of Kamilla and Cecile fleeing Ramsey's zombified thralls in their office building.
- One-Winged Angel: Ramsey takes on his monster form during his Final Battle with Barry, but shifts back after being distracted by a hallucination of his mother.
- Out of the Frying Pan: Team Flash successfully stops Ramsey's rampage once and for all, only to now come face to face with a multiversal apocalypse.
- Ray Gun: Cisco insists his photon emitter is not this. It basically is. Bonus points for it’s purpose being the same as when Cisco made Snart’s Cold Gun.
- Red Sky, Take Warning: The Crisis begins!
- Right for the Wrong Reasons: Iris believes that Dark Flash asking her to meet at their loft is a result of Barry Fighting from the Inside. She's right that Barry is resisting Ramsey's control, but calling her to the loft is a trap set by Ramsey.
- Sensory Overload: Exploited. Cecile feels the immense amount of fear of Ramsey's thralls and uses it on Kamilla's behest as a zombie detector.
- Shout-Out: The episode's whole premise, from Team Flash fighting off the Blood Brothers to Kamilla and Cecile sneaking through a building to evade them, brings to mind Resident Evil.
- So Proud of You: Cailtin tells Frost that she is proud of her handling of those difficult days.
- Something Only They Would Say: Cisco and Iris realize that Barry has some control over Ramsey when Ramsey had said that he chose Cisco as a leader. This way, they realize that Barry is somehow speaking through Ramsey to send a secret message to them.
- Special Edition Title: "The Flash" title is shown with Ramsey's infected blood.
- The Stinger: Nash being sucked into the Monitor's chamber. But unlike the other stingers this week, we see why Nash touched the Monitor's symbols.
- That Man Is Dead: Ramsey now insists on being called Bloodwork.
- Villain Has a Point: Ramsey states that Iris gave up on saving her husband from the upcoming Crisis, which is true.
- The Virus: Rosso is a metaphorical human virus, given that the episode focuses on him spreading his infected blood to everyone in sight.
- Voice of the Legion: Ramsey's voice now has a disturbing echo.
- Well-Intentioned Extremist: Ramsey is utterly convinced that he's the good guy, saving people by "curing" them of mortality.
- Wham Shot: The skies turning red at the stroke of midnight. The Crisis has begun.
- When the Clock Strikes Twelve: The Crisis begins with the sky turning red at exactly the stroke of midnight.
- World-Healing Wave: Allegra uses her powers on the Particle Accelerator to remove Bloodwork's control over his Blood Brothers.
- Zombie Apocalypse: Rosso's plan essentially starts one as he controls several people at once, and has them spread across the city.
