Warning: contains spoilers for Superman: Son of Kal-El #13!
In a vision shown to Superman, the Joker is proved to be the greatest threat to the Justice League, as his signature weapon wipes out the team with very little effort. The Joker tends to keep his schemes Gotham-centric, but with one small twist to his famous Joker Toxin, he could easily wreak havoc on the whole world. Not even Superman could stop the Joker if he chose to care about destroying anything beyond Batman.
The Joker has plagued Batman since 1940, when he made his first appearance in Batman #1 by Bill Finger, Bob Kane, and Jerry Robinson. Though the super-villain occasionally teams up with other villains outside of Gotham for the resources he requires, he primarily sticks to Gotham and the larger Bat-Family. His main — and most famous — weapon is his Joker Toxin, which causes the victim to break out in riotous laughter before quickly dying. Meanwhile, over in modern-day Metropolis, Jon Kent's Superman is currently battling the Gamorran president Henry Bendix, who continues to threaten Jon and his loved ones with his army of mind-controlled post-humans.
Related: Joker's Girlfriend Punchline Gets the Spotlight in New Series This Fall
The Joker Gas is used by Bendix — in a vision of the future — with deadly consequences in Superman: Son of Kal-El #13 by Tom Taylor, Nicole Maines, Clayton Henry, Matt Herms, Marcelo Maiolo, and Dave Sharpe. The just-introduced Dreamer presents Superman with a vision of an impending future in which Bendix drops a post-human made of Kryptonite-infused Joker Toxin on Gotham. When reinforcements are called in, not only do countless civilians die, but so does much of the Justice League and other heroes — including Batman, who
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