Shadow Serpent
From Mistipedia
The Shadow Serpent combines many of the worst aspects of an iron cobra and a shadow asp. It an extraordinary feat of ingenuity and was created by Easan the Mad. It was used successful, for a time, to assassinate Borcan aristocrats. It was used unsuccessfully in an attempted assassination of Lord Soth. The Order of the Guardians in Sithicus possessed it for a time and perhaps still does.