Spider-Man is not the only Marvel hero with an entire series devoted to the alternate versions of himself. In Venomverse by Cullen Bunn and Iban Coello, Venom worked alongside alternate symbiote wielders in a battle to stop a deadly army of anti-symbiotes called the Poisons. But their efforts to save the universe they were summoned to save unintentionally revealed a greater threat that now knew of a greater amount of territory to conquer.
The Doctor Strange of Earth-22249, bonded with the Venom symbiote, was faced with an army of Poisons led by a Poisoned Doctor Doom. The Poisons were as antithetical to the symbiotes as one could possibly be. They were a crystalline species that, due to their small size, were often hunted as prey by larger species. This would end when the Poisons first encountered the symbiotes. They discovered that they could assimilate symbiotes in addition to their hosts to make themselves stronger. This sparked an aggressive need for conquest from the once hunted species as they began tracking down and assimilating symbiote users.
This put them in the crosshairs of Doctor Strange. He had been hunting down the Venom symbiote initially, but when he discovered the Poisons he recognized them as the greater threat. Bonding with his former target, Doctor Strange used it as a beacon to pull various venomized heroes from across the multiverse to help stop this new threat. This brought in characters like Eddie Brock, Mary Jane Watson, and Peter Parker, all from different universes, alongside characters not typically associated with the Venom symbiote such as an alternate Captain America and Rocket Raccoon.
This symbiote resistance became the main enemy of the Poisons. But things came to a head when Doctor Strange was captured. The surviving members of the resistance instigated a rescue mission to free their leader, but by that time, Doctor Strange had gained a new understanding of the situation. By bringing in so many Venomized heroes to battle the Poisons, he was prolonging the very conflict he wished to end. Even worse, the Poisons had learned much from Doctor Strange's desperate call for help.
The Poisons now realized that they had outgrown the confines of their reality. If their threat was great enough to warrant help from other universes, then that also meant they were strong enough to invade those other universes, and expand their already formidable numbers. It was this realization that made Strange decide to isolate the Poisons and hope that he and the forces he had summoned had done enough to contain them.
Strange had Rocket Raccoon set off an explosion, in hopes of eliminating the Poisons and Doctor Doom in the process. Some of the Venoms died holding off the Poison onslaught, but Doctor Strange managed to safely return the others to their home dimensions at the cost of his own life. Although the Resistance managed to strike a severe blow against the Poisons, their victory was short-lived at best.
Strange's hopes that the Poisoned Doom would be destroyed were in vain. It was revealed that Doom had never been the the true leader of the Poisons. That honor belonged to a Poisoned Thanos, who now declared that the Poisons would find other magicians to help them expand their empire to the rest of the multiverse. And so, a desperate attempt to save one universe inadvertently placed infinitely more in harm's way.