The antimatter cannon was the ultimate weapon of mass destruction. It was invented by Mobius with a single purpose, spread antimatter across the multiverse in order to destroy all of the infinite Earths in existence.
The cannon was built and placed in the nexus between the multiverse and the netherverse, with its entrance in a tunnel underneath Central City on Earth-1. After retrieving the stranded Barry Allen of Earth-90 in the netherverse, the Anti-Monitor test-fired the weapon on Earth-2, completely destroying the universe.
On December 10, 2019, the cannon was unleashed on the entire multiverse, destroying every Earth until the Flash, Vibe, Killer Frost and Pariah discovered the machine under Central City, with the Flash of Earth-90 powering it. Vibe managed to get Barry off the treadmill, but this triggered a fail-safe that would destroy every Earth immediately. Pariah summoned Black Lightning from Earth-TUD5 to help contain the energy of the cannon and buy time to find a solution. Barry of Earth-1 decided to sacrifice himself by running backwards on the treadmill to cause the wave to recede, the stress of which would kill him. However, Barry of Earth-90 temporarily stole Barry of Earth-1's speed and took his place on the treadmill, succeeding in stopping the wave and saving Earth-1, the last Earth in existence, but disintegrating in the process.
Behind the scenes
- In the DC Comics, the antimatter cannon is the Anti-Monitor's weapon to wipe out the universe. It was powered by concentrated antimatter and the only way to destroy it was for the Flash to continually run around it and sacrificing himself in the process.