Viper sent Boomslang and Cobra under Copperhead's lead to poison the water supply of Washington DC. While escaping through the street, the three villains found the citizens turned into snake-men similar to their teammate Slither, from which they deduced the "poison" actually was a mutagenic agent. When they reached their escape ship, they were intercepted by the Captain and Diamondback. Boomslang threw one of his boomerangs to the Captain, but it was intercepted by the Captain's throwing shield which then hit Boomslang, knocking him out.
Boomslang remained with the Serpent Society after Viper left.