Curt Connors created an enervator to help remove the Lizard condition that was in his system and tested it on an Iguana. Unfortunately the Iguana became mutated and turned into a creature with memories of the Lizard. The Iguana then fought Spider-Man and the Lizard until both he and the Lizard fought Spider-Man together.
He was defeated when Spider-Man used a portable Enervator to increase his power while decreasing the Lizards. With his power over increased it seemed as if the Iguana exploded but in reality he was transformed back into his original form.
The Iguana had all of Curt Connors' memories and the Lizard's powers with none of Curt's humanity. He could hypnotize humans, scale walls, command other reptiles, use his claws and prehensile tail as weapons and was bulletproof, but was extremely light and temperature-sensitive.