NECROPHIDIUS

This creature appears to be the skeleton of a giant snake with a fanged human skull as a head.

It is totally silent, immune to sleep, charm and mind-affecting spells, immune to poison and will never need to check morale.

The necrophidius achieves surprise 50% of the time (1-3 on d6) and, if it is not itself surprised, it will execute the Dance of Death — a hypnotic, semi-magical swaying which rivets the attention of any victim observing the worm who fails to make his saving throw against magic. Failure means inability to act; treat as hypnotism. This allows the worm to advance and attack without opposition.

Its bite (1-8 hit points of damage) causes paralyzation unless the victim makes his saving throw (against magic - this is not a venom). The paralyzation lasts 1-4 turns.

Despite a number of characteristics to the contrary, the necrophidius is not a member of the undead class and cannot, for example, be turned by a cleric.

A necrophidius is created for one specific purpose and is therefore generally met in the role of assassin or guard — never as a wandering monster.

There are three ways of creating a necrophidius. The first is by means of a special magical tome, similar to a Manual of Golems. The second method is for a high-level magic-user to employ a limited wish, a geas, and a charm person. The third method is for a high-level cleric to employ quest, neutralize poison, prayer, silence, and snake charm. 

The materials include the complete articulated skeleton of a giant snake (poisonous or constrictor) and the skull of a cold-blooded murderer killed within the previous 24 hours. 

The cost is 500 gold pieces per hit point of the creature and it requires 10 days construction time.