Warning: The following article contains spoilers from Avengers: Tech On #5, on sale now from Marvel Comics.
Symbiotes are big in Marvel comics right now, and Avengers: Tech-On #5 (by Jim Zub, Jeffrey "Chamba" Cruz, and VC's Travis Lanham) just introduced a form of Venom that's arguably the most powerful of all the alien lifeforms. There's a lot of competition as far as powerful symbiote beings go, with beings like Carnage tipping the power scales of the mainstream universe, but this new multiversal monstrosity is in a class all it's own.
Tech-On Avengers follows a pretty simple premise: in an alternate universe, Iron Man shares his armor with an entire Avengers team after Red Skull uses broken shards of Infinity Stones to depower all of Earth's heroes. Captain America, Wolverine, and Spider-Man all make tech-suit appearances, and face off against a giant version of the symbiote Scream that has been powered with "Infinite Mirror Shard" (IMS) energy by the Skull.
Jealous of Scream's power increase, Venom stalks the giant symbiote throughout the issue until he finally drains her IMS. In a desperate bid for more power, the newly-powered symbiote latched onto the tech-suited Wolverine, who instantly vaporized what remained of Scream. With the fragmented Infinity Stone energy powering the Venom symbiote, Wolverine's mind was quickly overtaken. As he battles Captain America and Iron Man, a god-level Red Skull descends from the sky, promising to make things a whole lot harder for this armored team.
Carnage is typically seen as one of the most powerful symbiotes in the Marvel Universe, usually able to best Venom fairly easily. Unlike other symbiotes, Carnage refers to himself as I rather than we, indicating that Cletus Kasady and his suit are one and the same. His blood is fully replaced by the symbiote, and the gooey red being can replicate Cletus' body and consciousness even when Kasady is dead. But all of this isn't quite enough for it to outdo the power of the new Venom infused version of Wolverine seen in Tech-On.
Despite the IMS energy clearly making this Venom-Wolverine combination more powerful than any one symbiote, there are definitely more powerful symbiotic entities in the multiverse. Knull, the god of all symbiotes and darkness in the 616 universe, could easily overtake any symbiote as long as no cosmic light entities get in the way. Even with IMS powered energy, the Tech-On Venom is no match, because Knull would probably just steal any power contained within the symbiote. Additionally, now that the mainstream Eddie Brock has taken over the seat of Knull, it's highly unlikely that this alternate version would stand a chance against his mainstream counterpart.
While this IMS fueled Venom-Wolverine hybrid is no match for Knull or the current Venom of the 616, it's still the most powerful individual symbiote. In a universe currently lacking superpowered heroes, the power of this creature presents a serious threat that may end up being too much for the Avengers of his world to handle.