Demonomicon of Iggwilv
The Demonomicon of Iggwilv is a name that refers to one of three things connected to Dungeons & Dragons; a magical grimoire focused on the arts of demon-summoning, a series of articles in Dragon Magazine (and, in 4e, Dungeon Magazine as well) covering various Demon Princes, or a 4th edition sourcebook covering the Abyss. Its name comes from its author; Iggwilv, the legendary witch who first appeared in the Greyhawk setting.
The titular Grimoires are a set of six books written by Iggwilv containing her observations, understandings and strategems developed over centuries of studying the Abyss and the demons that dwell therein. These books abound in abyssal and demonic lore, outline practical methodology when it comes to demon summoning, detail various spells Iggwilv invented to augment her skills as a conjurer, and usually contain the Truenames of various demons. The specific contents of each grimoire vary, mostly in terms of what Truenames are present. Not helping the matter is that the Demonomicon has been copied by other wizards and abyssal witch-priests, creating diluted versions that have scattered across the cosmos.
The very first appearance of the Demonomicon is in the Advanced Dungeons & Dragons adventure S4 The Lost Caverns of Tsojcanth for AD&D 1st edition, where it is one of seven tomes found near the coffin of Iggwilv's vampire daughter, a warrior-woman named Drelnza. Later sources will claim that this is specifically the first volume of the six, having begun its life as Zagig's "Tome of Zyx" before Iggwilv stole it and began appending it with her own studies. This first version contains truenames, rules for magical circles and diagrams, and a bevvy of new spells; the cleric spells of Abjure, Exaction and Henley's Digit of Disruption, and the wizard spells of Dismissal, Dolor, Ensnarement, Banishment, Torment and Binding.
Another Iggwilv-written grimoire, "Lore of Subtle Communication", would be namedropped in Dragon #82's "Spells Between The Covers". It's unclear if this is part of the collective sextet that make up the Demonomicon, or if it's an entirely different book.
A third grimoire, "Iggwilv's Nethertome", would be mentioned in Dragon #225's Campaign Classics: "Three Greyhawk Grimoires"; again, we don't know if this is or isn't part of three Demonomicon proper. We do know that it includes a long treatise on the Blood War, chapters detailing the Abyss, including safe travel and places to avoid, a discussion of demon psychology, and a bevvy of spells. Most of these are common Conjuration-related spells - Protection from Evil, Contact Other Plane, Conjure Elemental, Invisible Stalker, etc. However, it also has two new offensive spells pioneered by Iggwilv; Lightning Cage (like a Forcecage, but with lightning) and Timeless Sleep (traps the victim in temporal stasis).
Third edition finally saw a "Demonomicon of Iggwilv" article in Dragon #336, which converted the in-universe grimoire into a set of lesser artifacts. As well as converting the unique spells from back when it first appeared in the Lost Caverns of Tsojcanth, the grimoires themselves are magical; they grant the bearer +5 caster level when casting spells with the "Evil" keyword, as well as bonuses to various skills, and each has 5 blank pages that can be used as the focus for spells like Magic Jar and Trap The Soul.
Finally, Dungeon #151 contained the adventure "Iggwilv's Legacy", a massive sequel-cum-revamp of the original Lost Caverns of Tsojcanth adventure.
Naturally, the grimoire's name was too good to pass up; beginning in issue #329, Dragon Magazine began featuring it as a semi-regular article examining the various Demon Princes, complete with examinations of their cults, "Thrall of (Name)" Prestige Classes for their chosen champions, and a 3e conversion of their most iconic associated demon species, ally or enemy.
In 4th edition, this inspired the creation of a whole family of articles with a similar purpose: Codex of Betrayal (Archdevils), Lords of Chaos (Archomentals) and Court of Stars (Archfey) - sadly, none of these ever had as many articles as the original did. 4e would also see the Demonomicon occasionally appear in issues of Dungeon Magazine as well.
For the complete list of articles, /tg/ has got you covered:
- Dragon #329: Pazuzu
- Dragon #333: Fraz Urb'luu (3e version)
- Dragon #337: Zuggtmoy
- Dragon #341: Baphomet (3e version)
- Dragon #345: Kostchtchie
- Dragon #349: Dagon
- Dragon #353: Malcanthet
- Dragon #357: Demogorgon
- Dragon #359: Apocrypha - new Loumara-type demon, the Manitou, and five minor Demon Princes:
- Dragon #360: Graz'zt
- Dragon #364: Yeenoghu
- Dungeon #172: Codricuhn, the Blood Storm
- Dungeon #188: Jubilex, the Faceless Lord
- Dragon #369: Baphomet (4e version)
- Dragon #376: Turaglas, the Ebon Maw
- Dungeon #205: Shemeshka the Marauder
- Dungeon #208: Fraz Urb'luu (4e version)
The 4e Demonomicon (lacking the "of Iggwilv" from its official title) was a successor to the earlier planar sourcebook, "The Plane Below: Secrets of the Elemental Chaos". Whilst that book had touched upon the Abyss to an extent, the bulk of its writings had been devoted to the Elemental Chaos, obviously enough. This sourcebook examined the Abyss in more detail, complete with a bevvy of new demons to pit the party against.