This is the third supplement for OD&D, and in some ways it is the most intriguing. It's certainly patchy, much like Supplement II, but the quality here is higher. What really stands out is the pulpy atmosphere, right down to the cover featuring a naked woman on a sacrificial altar. Demons? Druids? Psionics? It's a mix of D&D's most interesting and most maligned, but fascinating nonetheless.
The foreword gives an interesting snapshot of the game from this era – already the authors believed that things had become too predictable, with the players having too much access to the existing rules. Much of this supplement was supposedly designed to remedy this problem. Sure, it could all be ad copy, but it sounds plausible enough.
Psionics: The book begins with a short bit about psionics, and which characters can qualify for it. Those eligible are Fighters, Magic-Users, Clerics and Thieves, which is pretty much everybody. The question this raises is whether the various sub-classes like rangers and paladins also qualify. For the moment I say no – they get enough advantages as it is. Monks and Druids are specifically prohibited, which is fine by me. Psionic character also must be human, another balancing factor. Though given that humans already have unlimited level advancement, it seems like they're well overpowered by now.
Psionic fighters are said to have the powers of yoga, which any player of Street Fighter 2 will know makes them intrinsically awesome. The trade off is that the fighter must give up followers and Strength points for psionic power.
A psionic magic-user has to lose the ability to memorise one spell per day for every psionic power he acquires. A pretty good balancing factor, all told.
Psionic clerics are penalised in the same way as magic-users, and the also become less potent at turning undead. That last one warms the cockles of my DM heart, but as a player I don't think I'd want to risk it.
Thieves practise psionic yoga as well, and suffer the same penalties as fighters. In addition, they trade their powers for Dexterity.
So how do you figure out if your character is psionic? If you have an Intelligence, Wisdom or Charisma of 15 or more, you can check for psionic ability, with a 10% chance for success. If your character has psionic ability, you then roll on a chart for psychic potential, and this gives you a cumulative chance for each level gained that you will develop a specific power. Also, if you gain a power there's a smaller chance you'll immediately sprout another one. The accumulation of powers looks like it could get out of hand here, but at least they're selected at random. It still looks like a potential game-breaker to me, but I won't know until I've played it I guess.
So where do psionics come from in my game? If characters start spontaneously developing powers when none had done so before, then some outside force must be influencing things. The mind flayers seem like a possible way to explain things, as they are the first psionic beings introduced into the game. It may be that their recent forays to the surface have awakened the dark dreams and nightmares within the minds of man, unlocking the potential for some ultra-sensitive minds. That's what I'll go with for now, unless a better explanation presents itself.