Caelumancy is the term used in this book for truly potent weather and nature magic. It's described as a crafting feat, by analogy with making magic items, but effectively the powers listed here are spells that affect areas miles across for months at a time.

There are eight different weather effects, which tend to closely resemble spells such as Control Winds or Lightning Storm, except for the greatly increased duration and area of effect.

Most of the effects listed in the book, however, have nothing to do with weather: for example, a further fifteen relate to living things, and here resemble (without just duplicating) spells like Goodberry or Plant Growth.

Five further effects are described as "boons" and do things like changing all water in the vicinity into healing potions, while five are "wracks" and are more like Contagion. Four "apocalyptic" effects create things like earthquakes and volcanoes.

In addition to the effects themselves, there are some additional feats for their creators, a section on how to dispel such powerful magic, and a fair sized selection of ideas on how to combine different effects to produce weird bits of magical geography. Also, some of this weather can apparently become sentient - presumably because magic items can - which does, at least to me, feel a little odd.

Its all pretty powerful stuff, although, like magic items, creating it requires expenditure of XPs and large amounts of money (quite what the money is spent on is unclear, however). As magical effects that can bring flavour to a game world its actually pretty good, and there are also rules for things like extreme weather.

GMs might, however, be wary of actually giving these powers to PCs. But even so, they can be used as rules for creating unusual meteorological or geographical hazards in a high-magic world. The list of effects is fairly comprehensive, and doesn't simply duplicate more regular spells. There are some good ideas here, although you might want to be careful how you use them.

It goes without saying how most magic in the 3.5 RPG is tactical in nature. Because of this, it’s easy to forget the more wondrous aspects of magic from fiction and folklore. Spells that eternally turn a blasted desert into a lush rainforest, or a fertile valley into a dust-choked wasteland, are lost in the shuffle of new damage-dealing enchantments. In fact, it’s almost astonishing how much magic that permanently alters a local area’s ecology has been ignored up until now. However, this is a hole that is filled with Caelumancy, by Bards and Sages.

Caelumancy is, as noted above, the creation of permanent effects that affect an area. Interestingly, this system is treated as creating a magic item, taking the form of a spire on the Ethereal plane, which continues to create the effect on the Material plane so long as the spire remains. The obligatory new item creation feat is presented almost immediately, with the bulk of the book being the various types of caelumancy that can be made.

The various types of caelumancy are divided into five groups: those which affect the weather, the flora and fauna, boons (which enhance creatures), wracks (which harm creatures), and apocalyptic effects. The first two types have more specific types of caelumancy than the rest, but there’s still a fairly diverse number of effects altogether. After this, the book explores several related subjects, including additional feats related to caelumancy and magic item creation, the possibility of sentient caelumancy, how to destroy caelumancy spires on the Ethereal plane, and several example caelumancy effects.

Now book is without its flaws, however, and Caelumancy is no exception. Besides some minor issues (like the Caelumancy feat not being properly labeled as an item creation feat), there were a few things on the technical side that I noted. For example, the printer-friendly PDF actually keeps all of the book’s illustrations – it simply changes them to being grayscale. Why weren’t they simply removed entirely? At least the border on the facing pages was removed. Also, the bookmarks were extensive, but didn’t nest properly, meaning that sections and sub-sections among the bookmarks weren’t indented, making them harder to use.

Overall though, I was quite taken with this book, as it presented a neat new bit of d20 lore that seems to have been ignored up until now. Permanent weather effects are a great bit of magic to add to a game; I’m reminded of how, in The Lion, the Witch, and the Wardrobe, the White Witch made it so that Narnia was “always winter, but never Christmas.” If that isn’t the sort of evocative imagery that gets your imagination going, the example caelumancy effects at the end of the book might do the trick. Either way, the environmental-magic portrayed here is a great way of bringing a classic form of magic into your game.