These snakes typically lay in wait for prey, preferring wooded areas or swamps. 

They attack by bite and coiling to constrict. A successful coiling attack indicates automatic constriction damage each round thereafter. 

Any creature of humanoid sort can escape from coiling attack by Strength. This is indicated by a roll to Open Doors, penalized by +1 to the roll.

These monsters have heads at both ends, and both heads are armed with poisonous fangs. The creature travels by grasping one of its necks and rolling like a hoop. It is able to attack with both heads, and victims failing to save versus Poison when bitten die instantly. Cold-based attacks do not harm the amphisbaena.

These snakes usually drop coils from above, grab prey within their coils, deliver a bite, and then constrict causing 2-8 points of damage per melee round. If several strong creatures (such as 4 humans of 16 or greater Strength) can grasp the creature at head and tail ends, they can uncoil it in 2-5 melee rounds. After eating, the snake sleeps for a period of several days.

Giant poisonous snakes need no lengthy explanation or description. Some varieties, however, are worth noting, as their poison is so strong that even if a saving throw is made the victim takes up to 3-18 hit points damage.

Found only in tropical waters, these marine creatures attack only when hungry (20% chance). They otherwise ignore other creatures unless molested. Sea snakes have a poisonous bite. The largest are able to coil about small vessels and crush them at a rate of 10% of total value per melee round of constriction.