The bodies of death worms were bleached-white and their human-like heads had snake-like fangs. Their skulls seemed to have swirling white eyes, and their bodies emitted no odor. They were able to crawl completely silently, and could stand on the tip of their tail to elevate themselves to around 12 feet (3.7 meters).
These very rare creatures could understand Common, but were unable to speak. As well as this, they were adept at climbing, sneaking, and hiding. Although they appeared to be undead, they were not, much like a bone golem.
Owing to their stealthy nature, necrophidii would often hide and then launch a sneak attack on an opponent. If spotted in plain sight, these creatures could hypnotize prey by whirling in a specific manner, and then viciously bite their victims. This vicious bite could even paralyze a foe, and cause them to become unconscious for up to 10 minutes. They sometimes attacked in groups, causing their enemies to be flanked, giving the constructs an advantage in combat.
- A two-headed variant of necrophidius that was developed by the Zakharan necromancer Sumulael. He scribbled in the margins of his necrophidicon how one could extend the usual recipe for these golems in order to create his two-headed variant.
As these golems had no need for food or sleep, they did not have a large impact on ecology. However, they obeyed the word of their masters, and so could hunt down creatures in an area they were commanded to protect.
Necrophidius constructs were often made to serve as assassins or guards. The base cost for such a construct was 5,000 gp, but more powerful ones could be made. The spellcaster had to have the ability to craft wondrous items, as well as be willing to lose power in the production of such a construct, and five days spare.
The required components were a skeleton of a snake, a skull of a humanoid, and the material components needed for the individual spells. Arcane spellcasters required the usage of geas/quest, hold person, Mordenkainen's faithful hound, and hypnotism. Divine spellcasters required the same first two spells as a mage, but also needed animate objects and command. Other spell combinations were known to create a necrophidius, as well as differing expenditures in both gold and time.
- Eric Cagle, Jesse Decker, James Jacobs, Erik Mona, Matthew Sernett, Chris Thomasson, and James Wyatt (April 2003). Fiend Folio. (Wizards of the Coast), pp. 126–127. ISBN 0-7869-2780-1.
- Doug Stewart (June 1993). Monstrous Manual. (TSR, Inc), p. 170. ISBN 1-5607-6619-0.
- Don Turnbull (1981). Fiend Folio. (TSR Hobbies), p. 67. ISBN 0-9356-9621-0.
- Steve Kurtz (1994). Al-Qadim: Cities of Bone: Campaign Guide. (TSR, Inc), p. 24. ISBN 1-56076-847.
- Grant Boucher, William W. Connors, Steve Gilbert, Bruce Nesmith, Christopher Mortika, Skip Williams (April 1990). Monstrous Compendium Greyhawk Adventures Appendix. Edited by Mike Breault. (TSR, Inc.), p. 41. ISBN 0-88038-836-6.
- William W. Connors (1996). Monstrous Compendium - Ravenloft Appendices I & II. (TSR, Inc.), p. 71. ISBN 0786903929.
- R.A. Salvatore (March 2013). The Last Threshold. (Wizards of the Coast). ISBN 0-7869-6364-6.
- Ed Greenwood (1991). “Campaign Guide to Undermountain”. In Steven E. Schend ed. The Ruins of Undermountain (TSR, Inc.), p. 34. ISBN 1-5607-6061-3.
Flesh (Blood • Brain • Demonflesh • Fiendish flesh • Nyraala) • Gemstone (Diamond • Emerald • Ruby)
Gloom • Hammer • Ice • Iron (Furnace) • Lightning • Magic • Minogon • Necrophidius • Rag & String • Sand • Scarecrow • Siege golem • Snow
Stained glass • Stone (Gargoyle • Spiderstone • Stone guardian • Stone juggernaut) • Thayan golem • Vault guardian