A Xen-Viper is believed by many to be a highly adaptable - and quite recent - creation of the Caarth, since they share physiological similarities with other such beings as well as ideological ones, and are known to serve other reptilian races. However, given both this facet of their personality and the fact that they are warm-blooded has led some to suggest that they are in fact a species that has evolved naturally or been created by a god, perhaps the Snake Goddess Vermistra.
Despite being covered with scales and lapsing into a hiss-filled variant of the Common Tongue in times of stress, a Xen-Viper possesses an extraordinary ability to blend in, its disguises often going unnoticed save by fellow masters of this art. This makes Xen-Vipers extremely adept assassins and spies, as was the case with Lishek, a female who served under Karam Gruul for a short period of time.
Xen-Vipers make extensive use of poison as a means of spreading death, discharging a highly potent toxin from a pair of retractable fangs, this adaptation enabling them to fit it far more easily. A Xen-Viper requires several hours to "regenerate" its poison should it be discharged all at once, in common with other Poisonous Snakes.