Amphisbaena is portrayed as a stout-bodied reptile covered with both scales and hair. Its secondary head is in the guise of a maiden from head to hips, who is attached to the main body via a long, upright tail. This feature seems to be unique to Castlevania and forms the basis of the creature's offensive options, consisting primarily of fireballs (spitted only by the maiden's head). The player is able to stand on the reptile portion of the body without being harmed. Attacking the maiden will cause her to flinch back but she will not take any damage.
The amphisbaena is a mythological, ant-eating serpent with a head at each end. The creature is alternately called the "Mother of Ants". Its name comes from the Greek words amphis, meaning "both ways", and bainein, meaning "to go", roughly translating as "to go both ways", a name which describes the presence of a head on both ends of its body.
According to Greek mythology, the amphisbaena was spawned from the blood that dripped from the Gorgon Medusa's head, as Perseus flew over the Libyan Desert with it in his hand, after which Cato's army then encountered it along with other serpents on the march. Amphisbaenae fed off of the corpses left behind.
The Amphisbaena is a wielder of many abilities, including venom, hypnosis and blinding speed; however, these vary within the numerous accounts it is mentioned in. Physically, the Amphisbaena has resembled a snake, a dragon and a basilisk, all with two heads.
Renamed as Diplocephalus in the American version of Symphony of the Night, the player encounters this creature early in the game as one of their first considerable challenges, due to its relative high stamina at the moment it is encountered. Three of them can be encountered guarding a long corridor in the Marble Gallery. If the player attacks the mouth of the reptile-like head, it will retreat a few steps without attacking. A couple of Holy Water vials can quickly dispatch of them, and as long as the player attacks them constantly, without giving them chance to retaliate, they're not very difficult.
When defeated, the maiden will shriek in pain while she and the rest of the creature's tail slowly consume in flames, then the rest of the monster will burst and break apart.
Amphisbaena's appearance in Portrait of Ruin is even less prominent than its Symphony of the Night counterpart. A couple of them can be encountered in Sandy Grave, each one inhabiting one room and alone. Due to the player's ability to deal more and constant damage in more varied ways, they can be dispatched very quickly and from a safe distance, without even giving them chance to counterattack.
The maiden will fade away, shrieking in pain, while the reptile portion of the body collapses and remains on the floor after dying.