The Flash's Justice League Easter Egg Reveals How Powerful Barry Really Is
Warning: SPOILERS for The Flash season 7, episode 2, "The Speed of Thought".
The Flash season 7 confirmed just how powerful Barry Allen has become with an Easter egg tying into a classic Justice League comic book storyline. This was revealed through a refined Babel Protocol, designed to neutralize Flash if he ever became a danger to himself or the world.
First mentioned in The Flash season 4 episode "Mixed Signals", the Babel Protocol was a countermeasure Cisco Ramon devised to cope with a Flash running amok, either honestly going mad with power or being manipulated by one of the many metahumans capable of mind-control. The name was a nod to Tower of Babel; a storyline in the Justice League comic book, in which the team was attacked and neutralized by Ra's Al Ghul and the League of Assassins, using plans and specialized weapons that had been designed by Batman. In the Arrowverse, the original Babel Protocol was a self-destruct device installed in Flash's suit, which Cisco could activate remotely. In The Flash season 6, the Babel Protocol was expanded to include a force-field which isolated STAR Labs from the outside world, ensuring that a Bloodwork-possessed Flash couldn't get to the people most likely to stop him.
The action of The Flash episode "The Speed of Thought" centered around Barry Allen's development of enhanced cognition (i.e. super speed thinking) after bonding with a new Artificial Speed Force. Unfortunately, Barry's heightened intelligence came at a cost; the faster he thought logically, the more emotionally detached Flash became from the people around him. Cisco was the first to notice Barry's odd behavior, when Barry hesitated in stopping Frost from being shot by Mirror Mistress, reasoning that he could easily treat her injuries later with no real risk. This resulted in Flash facing off against Team Flash, showcasing just how powerful Barry Allen has become when he fended them off.
When it became apparent how far gone Flash was, Cisco unveiled the latest Babel Protocol; one that wasn't "just force fields and tech." The scene which followed was the action high-point of the episode, as Flash was forced to face three of his friends at once, all of them armed with multiple means of stopping him. Cisco wielded a modified anti-speedster gun firing charges of what he dubbed Velocity-Zero, which could temporarily suppress Barry's powers. Not to be outdone, Frost (whose cold powers could also be used to slow down a speedster) was armed with the Velocity-X drug that temporarily gave her super speed and the power to throw electrically-charged ice blasts. Finally, there was Allegra Garcia, a light manipulating metahuman, who was armed with the same teleporting smoke bombs utilized by Nash Wells and a crystal that, used in conjunction with her powers, allowed her to generate a ray that caused people to relive the worst moments of their lives.
While Flash was ultimately able to win the fight, it was only due to his ability to flawlessly predict what his allies would do after determining how they were armed. Regardless, the fight showcased just how powerful Barry now is in the world of the Arrowverse. It also proved Cisco Ramon's brilliance as a tactician, as Barry was briefly left floundering and off-balance thanks to Cisco's preparation and a team effort worthy of the Justice League.