The Basics
Armies of the Abyss is a 64-page perfect bound d20 supplement from Green Ronin Publishing. It is subtitled "Book of Fiends, Volume Two" (Volume One being "Legions of Hell.") The book utilizes the inside of both the front and back covers and contains no advertising. It is printed in black and white with tight text in a small but very readable point size and very reasonable margins.
The cover art, by Brom, depicts a muscular, winged demon atop a stony crag. This piece is not as interesting as his cover for Legions of Hell. The back cover art, by Brian Despain, depicts a blue-skinned demon master of torture and is a more interesting piece.
The interior art ranges from good to excellent, though it doesn't quite match in style from one illustration to the next. The only real complaint I have about the art is that there's not an illustration for every demon prince (only about half). The "standard" tanar'ri and qlippoth are all illustrated, however.
Chapter One: Into the Abyss
The book begins with a short exposition on the general character of the Abyss and its inhabitants, and the reasons demons might be interested in the Material Plane and your campaign in particular. This text really serves as a sort of introduction to the rest of the book, and is quite readable.
The chapter quickly introduces the qlippoth, thought to be the primordial inhabitants of the Abyss. Their destruction at the hands of their mortal enemies, the celestial eladrin, paved the way for their tanar'ri slaves to become the dominant race of the Abyss. "Qualities" blocks are given for both the qlippoth and tanar'ri monster types (the latter's is reprinted from the SRD).
The next section gives the basic rundown on demon lords and princes, including ascension via conquest of Abyssal layers and gathering mortal souls. It also gives a description of the arrival and "life" of souls doomed to the Abyss.
Chapter Two: Those Who Serve
This chapter introduces a new core character class, called the Thaumaturge. These characters are similar to clerics, but instead of receiving their spells as a divine blessing, they receive them from demonic patrons in exchange for an ever increasing personal corruption. The class receives domain spells and powers as clerics do, but gains the summon familiar abilities of the arcane classes in lieu of turning/rebuking.
This class is quite well done and interesting. They cannot take levels of Cleric without losing all benefits of the Thaumaturge class permanently. As they gain levels, Thaumaturges must periodically roll on a table of "Corruptions," each of which adds some taint of chaos. Some of these, such as fangs and irises of fire, are beneficial, adding a "corruption bonus" to skills (usually Intimidate). Most, however, are neutral or harmful, such as a raspy voice or unpleasant odor, and the worst of these give either corruption penalties to certain skills or ability loss (mainly charisma). As the character's level in Thaumaturge approaches the Epic threshold, he begins to roll on a "Greater Corruptions" table, gaining much more drastic marks of chaos.
Four new feats specifically designed for the Thaumaturge complete the chapter.
Chapter Three: Those Who Rule
Note: According to the back cover, 22 demon princes are described in this chapter, but I've counted multiple times and unless I'm just blind, there are only 21 entries. They may be including the qlippoth lord described in Chapter Four in that count, but if so, they ought to count the two tanar'ri lords in that chapter as well, I would think.
Each demon prince is given a short stat block in a manner similar to the deities in Core Rulebook I detailing their formal titles, the layer they control, their areas of concern, domains granted to their Thaumaturge followers, and their favored weapon. The descriptive text that follows details the character of each demon prince (by their very nature, they share few similarities), the physical forms they tend to manifest, the appearance and character of the layers they control, and the types of mortals likely to follow them. An additional section at the end of each entry describes the rites and rituals that Thaumaturges loyal to the demon prince must perform in order to replenish their spells. Some of these are quite grisly.
The demon princes are all well done and interesting, offering a very wide variety of goals and lusts for eager DMs to build truly bizarre villains and organizations around. The best thing about them is that not all of them are your stereotypical demonic engines of destruction. Ipos, for instance is called the "Lord of Masques" and is the patron of depraved actors. He rules over the Abyssal layer called the Festive Everlasting, where a dead actor's doomed soul can suffer the ultimate punishment: destruction by critic.
The chapter is rounded out by a page giving only the basic stat block and thaumaturge obedience information for several well-known demon princes not detailed in this book for Product Identity reasons, such as Orcus, Demogorgon, etc.
Chapter Four: Creatures of the Abyss
This chapter details 26 new tanar'ri, qlippoth, and other Abyssal locals, ranging from CR2 to CR25. The stat blocks for each are well done and include information not found in the standard monster stat block, such as Flat-Footed and Touch AC.
The individual entries are a bit text-heavy, leading to the impression that a bit of trimming might have found space for three or four more demons. Although it is difficult to assess Challenge Ratings at higher levels, these seem to be fairly accurate, for the most part.
Highlights of this chapter include a new type of construct (the "Razorwire Golem"), a good candidate for Improved Familiar (or the new feat "Abyssal Familiar" presented in this book) called the Mandragora, and the Incubus (the male version of the succubus, but a very different beast). Only the Armageddon Beast (which makes the Tarrasque look like a total wuss) seems a bit of a waste of space, as its usefulness as anything other than a plot device is doubtful.
Appendix I: Demonic Magic
A whole slough of new domains starts this chapter off well, adding Catastrophe, Change, Crippling, Disease, Eloquence, Fear, Pain, Pleasure, Prophecy and Subterfuge to the repertoire of Thaumaturges and evil clerics everywhere.
Nine new spells follow, most of which are exclusive to the aforementioned domains. These include appropriately hideous curses such as femurburst and fleshy blight as well as some perfectly evil spells used to seduce mortals to the dark side, such as phantasmal lover.
Rounding out the chapter is a brief (but more than adequate) description of six new diseases for use with the new spell greater contagion including the horrifying "Kobold Stank." Nuff said, really.
Two more appendicies appear on the inside of the back cover. Appendix II lists the creatures from Chapter Four by Challenge Rating, while Appendix III provides a brief bibliography of demonic information.
Overall
This is one of the best non-Wizards d20 products I've seen to date. It is a perfect companion piece to Legions of Hell and surpasses that book in both design and content. At 64 pages, it feels like it has considerably more useable gaming goodness than the average 96 page d20 supplement. At $14.95 you cannot go wrong.
Go to forum!
(Due to spamming, old forum discussions are no linked.)