With the rank-and-file demons out of the way, we move to the Demon Princes. It's noted that there are several such Princes, but Supplement III only has details on Orcus and Demogorgon.
ORCUS: This demon lord is 15' tall, grossly fat, with the head and legs of a goat, the wings of a bat and a poisonous tail. The picture of him that is provided is pretty cool if simplistic, and has remained the basis for the character's depiction all the way up to 4th Edition.
In terms of powers, this guy gets it all: High intelligence, 85% magic resistance, and immunity to all weapons of less than +3 enchantment. Shall I list his at-will abilities, just for fun? Oh yes I shall: continual darkness, charm person, create illusion, cause fear, detect magic, read magic, read languages, detect invisible, ESP, pyrotechnics, dispel magic, clairvoyance, clairaudience, lightning bolt (12 dice!), suggestion, polymorph self, wall of fire, telekinesis, speak with dead and animate dead. Not enough for you? He also gets these once a day: feeblemind, project image, any of the symbol spells, polymorph any object, shape change, and time stop. Oh, and he has an 80% chance of gating in any other type of demon. He'll never gate in another Prince, which is a nice hint about the nature of demonic politics, but at that stage it's probably a moot point.
The list above does speak to the way the game has developed with 4th edition. Even at this early stage, monsters had a bunch of special abilities. 4e pared them right back, citing that things had become too complicated, and I agree that by 3rd edition they had. But in OD&D I feel it works, mostly because you can pretty confidently just look at the name of the ability and extrapolate its effects off the top of your head. That's the beauty of one paragraph spell descriptions.
But I digress. Moving back to Orcus, we discover that he can summon certain members of the undead because he is their Prince. This ability is a doozy, even moreso than the power to gate in other demons. 2-8 vampires are going to ruin your day, you know?
Orcus also wields the Wand of Death, which is made of obsidian and topped with a skull. It's very metal. Anyone touched by it is killed or annihilated unless they're on Orcus's level - that includes other Demon Princes, High Devils, Saints, and Godlings, all of which have been hinted at in Gary's revision of alignment.
DEMOGORGON: Gary was really firing up the imagination when he came up with this guy. He's 18' tall, with the scaly body and legs of a giant lizard. His arms are tentacles, and he has two heads, each of which resembles an evil baboon. I've always thought baboons were kind of creepy looking, so kudos on that. He's rumoured to be supreme among demons, and able to command all cold-blooded creatures, such as snakes and octopi.
As for spell-like powers, I won't list them, as they're pretty much the same as those of Orcus with a few swapped around here and there. Demogorgon can't animate or speak with the dead, for example, but he does get Power Word Stun.
In addition, DG has a hypnotic gaze, and if he fixes the stare of both heads he can hypnotise a whole bunch of guys depending on their hit dice. Anyone under 15 hit dice is affected automatically, but luckily the commands are obeyed for just a few rounds. If just the left head gazes, it works as a Rod of Beguiling, and if the right head gazes it causes insanity.
And just so you don't get the idea to melee this guy, his tail causes level drain of 1-4 levels. And his tentacles rot any body part they touch, making limbs fall off in 6 rounds. It's not quite as final as Orcus's Wand of Death, but there's something even more horrifying about having your arm rot than just being instantly annihilated.
DEMON AMULETS: It turns out that the Demon Princes, and lesser Demon Lords, have their souls contained in amulets. Anyone who possesses the amulet has power over the demon, though not for more than a day. After that the wielder has to return it to the demon, or else can destroy it and exile the demon to the Abyss for a year. Presumably such treatment would not be looked on kindly when the year is up... There are other dangers of carrying one of these, as it doubles the chance of a demon hearing when you say his name, and any demon you're not controlling will instantly attack you. In general any demon thus commanded is going to be pissed off, but there's a slim chance that exorbitant payment for aid rendered, and careful return of the amulet, will placate it. But because this is Gary, it's couched in terms that make it seem highly unlikely.
Oh, and to finish up, we get the psionic strengths of the various demons, all of which have psionic power except for Type I.
NEXT: More monsters of the crazy variety.