The DC crossover Multiversity is one of the most expansive and ambitious superhero stories ever, bringing together heroes from across all of the DC multiverse to fight back against an army of dark monsters called the Gentry in an ambitious tale masterminded by Grant Morrison.
One of thee Gentury's more insidious ways of infecting the world comes with their corrupted and cursed comics. One of them takes the form of Ultra Comics, a product of Prime Earth that targets characters on all of DC's alternate earths and even supposedly targets the real-world reader.
The Orrey Of Worlds
Multiversity has a genuinely massive cast of heroes. The overarching narrative centers around the Gentry, a group of monumentally dangerous celestial beings. Their mission is to bring the multiverse down to their level, corrupting everything into darkness. They're powerful enough to wipe out entire realities and decimated the heroes of Earth-7 with ease. They even possess the ability to corrupt Nix Uotan, the last Monitor, who they turned into one of their number.
Their plans infect multiple realities across the multiverse, forcing different versions of heroes to band together to fight back against them. Although some realities are overtaken and destroyed by the process, others manage to fight back and repel their intentions. This even leads to some heroes coming together around the interdimensional House of Heroes to try and fight back against the infections that target and corrupt their universes.
One of the most nefarious plans of the Gentry comes from Earth-33, which is otherwise known as Prime Earth, which is a largely under-powered reality with almost no heroes. Within the DC Universe, it's the connection to the real world. The first superhero on the planet was Ultraa, the star of the in-universe story Ultra Comics, which was developed as a potential weapon to fight a mysterious being identified as a Hostile Independent Thought-Form. Ultra Comics was designed to contain the malevolent presence. He's designed as a self-aware idea and comic book, built to trap the Hostile Independent Thought-Form.
The reader essentially powers Ultraa, fueling him by reading the story. He travels to a post-apocalyptic New York and confronts not only a cannibalistic mob of children but the previous versions of Ultra from the last few decades. But in the end, the Gentry is actually able to turn Ultra Comics against itself. The Gentry reveals that they've used Ultra Comics to target readers across the multiverse, opening up their minds to the Gentry. The Gentry then forcibly age up Ultraa to the point where he's on the verge of death. Although Ultraa escapes, he's barely able to warn the reader before being locked into a loop within the comic, repeating around and containing the Gentry in some form, but everyone who reads the comic is infected by its influence.
Don't Read This Story!
Ultra Comics appears in many realities around the multiverse. It's even classified as a cursed artifact by the Doctor Fate of Earth-20. Any person who reads the book will open themselves up to the Gentry and can be affected by its influence. It's one of the ways that the Gentry is targeting all of the other realities, spreading its power and corruption around the multiverse. It even tries to affect the actual reader of the comic, wasting their time and mental faculties on everything that the Gentry touches. Alexis Luthor, the daughter of Lex Luthor from Earth-16, reads the "haunted" comic and is infected with malicious intentions to help bring down her world.
Eventually, the Gentry is confronted by the assembled heroes, who are able to free Nix Uotan and turn him back to the side of good. Uotan is able to help fight back against the Gentry, and reveal that he brought together all the superheroes of the multiverse to help. The Gentry is seemingly defeated, but their forces spread from the ruins of Earth-7. Their master the Empty Hand banishes the heroes away, which leads to the formation of Justice Incarnate. They even learn the origins of Ultra Comics from Earth-33, and President Calvin Ellis, the Superman of Earth-23 who decides that Justice Incarnate will protect the DC Multiverse from existential threats like the Gentry.