While reading Occult Adventures, some people may be surprised that it doesn't contain any new monsters. Roleplaying books of this sort will often contain a selection of new monsters that serve both to illustrate how the new rules are used and to provide GMs with some ready-made opponents for PCs built with the new rules. Mythic Adventures, for example, has a small selection of mythic monsters for just these purposes, yet Occult Adventures has none.
The introduction to Occult Bestiary reveals that the original plan was to have a few monsters in Occult Adventures, but the limits of space meant that it just couldn't be. To have included the monsters would have meant leaving out something else. As nice as new monsters can be, it's a decision I'm glad they made as there is so much flavourful material in Occult Adventures, that there's very little I could imagine leaving out. Nevertheless, the new rules cry out for monsters that use them, and Occult Bestiary answers that cry.
Occult Bestiary contains all the monsters originally planned for Occult Adventures, plus dozens more. Now, the book is part of the Pathfinder Campaign Setting line, which means that the monsters within are tied to Golarion, whereas Occult Adventures is setting-neutral and thus any monsters that had appeared there would have been setting-neutral as well. However, it makes little difference in the end. While Occult Bestiary does use a few Golarion terms and locations, all the monsters within are easily divorced from the setting. Indeed, most of them make no explicit reference to Golarion at all. As such, this book is easily used with any campaign setting.
The book begins with a few new universal monster rules before starting into the monsters themselves. Chief amongst these is psychic magic, which is essentially a new way of handling spell-like abilities for psychic spells. This is the only thing in Occult Bestiary that I don't particularly like as it adds a completely unneeded subsystem. Psychic magic lets monsters use psychic spells by spending “psychic energy” (PE), in contrast to the uses per day that spell-like abilities normally have. The stat blocks of monsters that use psychic energy list the number of PE the monsters have per day (refreshed over night) and the PE cost for each of the psychic spells.
I really don't see the need for this. While psychic spells are meant to have a different feel to them, they are still just a third type of spells. Many psychic spells can also be cast as arcane or divine spells. Separating them here seems more like hearkening back to old psionic power point systems that Occult Adventures has deliberately moved away from. It's further confounded by the fact that numerous monsters have spell-like abilities that include psychic spells in the list. Why should some use psychic energy and others have uses per day?
It's not a difficult system and it's easy enough to use. However, it does create an extra thing for GMs to deal with in combat when they already have a lot to keep track of. It's further exacerbated by the monsters in the book that have both psychic magic and spell-like abilities—and there are quite a few of those. It can be difficult enough at the best of times to keep track of what abilities a monsters has used and what it hasn't. To track some via uses per day and others via psychic energy just adds to the headache (and while there aren't any examples in this book, I can just imagine the even greater headache of a creature that has psychic magic, spell-like abilities, and can cast spells normally, too). Having the two systems also seems to have created some confusion on where to list them in the stat blocks. Of the monsters that have both psychic magic and spell-like abilities, some list psychic magic first and others list spell-like abilities first. I honestly think psychic magic should have just been handled as spell-like abilities. It doesn't need a separate subsystem.
But oddities of rules subsystems aside, I love the monsters in this book. There's a large variety in monster type (pretty much every type except animal and vermin are represented), alignment, role, and general feel. Challenge ratings range from ½ (the reborn samsaran) to 23 (Tychilarius, a unique creature from outer space, sometimes called the Drowned God). Most of the monsters get one page for stats and description, although some get two pages. It would be nice if every creature could get two pages, as those that do, get more descriptive text and as a result, tend to be the ones absolutely oozing with flavour. However, there is strong flavour with all the monsters, even the unfortunate ones that end up with only a single paragraph of descriptive text.
It would be impossible for me to comment on every monster in the book individually (I'd have to practically rewrite the book to do that), but I would like to comment on a few that particularly caught my interest. The mnemor devil can alter people's memories, but as with all devils, does so at a price, providing new memories that may be worse than the ones the subjects were originally trying to get rid of. Sometimes, mnemor devils will also make people forget that they sought a deal in the first place, meaning they'll keep going back to the devil to change their memories.
A prana ghost is similar to a regular ghost except that it has a good alignment... and it's not undead. It is the spirit of a dead person, but it's made of “vital life essence” (prana) and not powered by the negative energy that powers undead. It does come across as a bit of a work-around to avoid having a good undead, but I do like the fact that undead that feed on life energy are drawn to prana ghosts to feed on them.
The prism dragon is the epitome of the chaotic neutral alignment. Prism dragons like to concoct extremely complicated schemes—not because they are overconfident, but because they know the added complexity makes it more likely the schemes will go wrong and thus, they can test their ability to improvise and compensate. They still don't like it when they lose though.
Several creatures have abilities that affect people's dreams, such as baku dreamweavers (who get simply the cutest artwork in the book), dreamthief hags, and dream nagas. Each of these creatures affects dreams in a different way. Dreamthief hags actually capture and imprison dreaming minds, while dream nagas simply enter people's dreams to interact with them in ways that the dreamers generally don't understand. Baku dreamweavers feed on dreams like standard bakus (from Bestiary 3), but also have the ability to change and manipulate people's dreams.
Although I don't tend to comment a lot about artwork in my reviews, no book of monsters is complete without the art, so it would be remiss of me not to mention it here. Occult Bestiary has some very evocative art to accompany the monster descriptions. The dream naga is one of my favourite pictures in the book, but there are numerous other great pictures as well. Only a couple don't work as effectively as they could. The picture of the yithian elder with its entry inside the book looks rather cartoonish and comical, which is a huge contrast to the cover picture which evokes a much more terrifying creature. I much prefer the cover picture in this case (the yithian elder is the multi-eyed creature with spindly, almost tentacle-like appendages and large claws).
Monsters enjoy an interesting privilege in roleplaying games. It seems that no matter how many there are, there are never too many. There are a lot of monsters in Pathfinder and there's a very good chance that many of the ones in Occult Bestiary will never see use in any of my games. But I like having them nevertheless. And some will see use. Maybe a lot of use. Overall, Occult Bestiary is a great addition to any GM's bookshelf.