Xill were vaguely reptilian creatures with flame-red, leathery skin and solid black eyes. They had roughly humanoid bodies about 4‒5 ft (1.2‒1.5 m) tall, with four clawed arms. Xill weighed about 100 lb (45 kg) on average. High Clan xill would wear clothing and jewelry; Lower Clan xill wore absolutely nothing.
There was little difference between the natural abilities of the Lower and High Clan xill. All xill could shift between the Border Ethereal and Material planes at will, and could take a willing or helpless creature with them while doing so. They had paralyzing venom delivered via a bite, although the venom glands did not produce very much venom: Lower Clan xill could bite twice every six hours, while High Clan xill (in whom the venom glands had atrophied due to disuse), there was only enough for one bite each day. Xill had no spoken language, because they were naturally telepathic.
Lower Clan xill used their innate planeshifting ability to ambush creatures on the Material plane, attacking to subdue and capture a victim. They carried no weapons and bore no armor, instead using their four clawed arms to attack with. If attacked in their lair on the Ethereal plane, they would first move any young or egg-carrying prisoners to a safe place before attacking their enemies.
High Clan xill would use both armor and weapons, preferring to carry weapons in two hands while leaving the other two free to grab and hold enemies in melee. Thye used their paralyzing venom only as a last resort.
All xill could be classified as members of either the High Clans or the Lower Clans. However, Lower Clan xill did not call themselves as such or even acknowledge that the High Clans existed; they were wholy barbaric and apparently lived only to reproduce. Lower Clan xill saw all other species as prey.
Higher Clan xill were civilized, making and using weapons, clothing, tools, and other such things; trading with other peoples; building cities in the Deep Ethereal (on chunks of what was called solid ether). Although they rarely left the Ethereal Plane, they did not consider all other species prey and some were even willing to work as guides on their homeplane.
High Clan xill sometimes became clerics, who were known to act as leaders of small groups of xill. Xill clerics would worship a variety of deities, and were known to access spells from, variously, the Evil, Law, Strength, and Travel domains.
Xill were only known to dwell in the Ethereal plane, inhabiting both the Border and Deep Ethereal; xill hunting on the Material plane could be found in any climate on land. They were omnivorous. Xill had a lifespan of about 50 years.
Xill reproduced asexually, with each xill laying two sets of eggs (numbering 2-16 eggs in each laying) during their life. However, xill eggs had to be implanted in a living, intelligent host; Lower Clan xill preferred to lay their eggs in magic-bearing hosts. The eggs were implanted into the gut, where they remained for about four days before hatching, after which the larvae grew within the host for about seven days before emerging, a process that was almost certainly fatal for the unfortunate host. The unhatched eggs could be removed by a cure disease spell, but only wish or limited wish could remove the larvae. Xill grew to adulthood in 1-4 hours after emerging.
High Clan xill did not speak of their own reproductive habits, but it was rumored that they still required intelligent hosts, and kept a massive prison/hatchery hidden in the Deep Ethereal where human slaves were bred and raised like livestock for just that purpose. These slaves, supposedly, were the descendents of victims captured long ago; they had also lost any trace of civilization and rarely lived past late adolescence before serving as a hatchery.
Some scholars claimed the xill actually came from a demiplane in the Ethereal plane, and linked them with the mysterious wizard Keraptis. They claimed that he created the demiplane, and the xill as servants, utilizing their planeshifting ability to collect artifacts and people.
- Computer Games
- Dungeon Hack
- Mike Mearls, Bart Carroll, Bill Benham (December 2019). Mordenkainen's Fiendish Folio, Volume 1: Monsters Malevolent and Benign. (Wizards of the Coast), p. 21.
- Skip Williams, Jonathan Tweet, Monte Cook (July 2003). Monster Manual v.3.5. (Wizards of the Coast), p. 259. ISBN 0-7869-2893-X.
- Tim Beach, Donald J. Bingle, Al Boyce, Vince Garcia, Kris Hardinger, Steve Hardinger, Rob Nicholls, Wes Nicholson, Norm Ritchie, Greg Swedberg, and John Terra (1992). Monstrous Compendium Fiend Folio Appendix (MC14). (TSR, Inc), p. 63. ISBN 1-56076-428-7.
- Monte Cook, ed. (1998). Monstrous Compendium Planescape Appendix III. Edited by Michele Carter and Ray Vallese. (TSR, Inc.), pp. 120–121. ISBN 0-7869-0751-7.
- Don Turnbull (1981). Fiend Folio. (TSR Hobbies), p. 96. ISBN 0-9356-9621-0.