This supplement for Mage is an excellent source book for diversifying your games. The main focus of this book is on "dead" magic: the forgotten magics of civilizations of yore. The book has lots of rotes, wonders and so forth, but the bulk of the book is about how these civilizations practiced magic, and how the Traditions (namely your players) can adapt it.
The first section covers the magic of sub-Saharan Africa, with a definate focus on western and southern Africa. Lots of details on the diversity of African culture (and a nice map too), along with how westerners (including most of the Traditions except maybe the Dreamspeakers) have marginalized African culture. Then we are given some sample African rotes, many focusing on fertility, healing and spirit magics, and some pretty nifty wonders. There are also some interesting supertnatural creatures and locations, in case you decide to run a game set in Africa.
Following this is a section on ancient Mesopotamian magic. While I wish they would have toned down the infernalism a bit, this was a pretty nice section. Alot of it revolved around the meta-plot too, tying it in with Hermetics rediscovering Mesopotamian magic. Alot of the Mesopotamian magic focuses on complex divinations and spirit controlling magics. There is also a bit devoted to adapting Mesopotamian magic to the modern Traditions. Although groups like the Hermetics and Verbena usually use these in their ancient forms, modern Traditions have some unique takes on these rotes. Very nice. There are also some Mesopotamian beings (including the Lamassu!).
The next chapter was one of the best, in my opinions, focusing on the bloody magics of Mexico and South America. WW is pretty direct and to the point, stating that the Mayas, Aztecs, Incas and other Native Americans here used human sacrifices and that their magics were not for the weak. A bit of this chapter is taken up by an explanation of the Mayan calendar (which probably could have been briefer). Regardless, the sample rotes (including things like turning into a jaguar, making obsidian almost unbreakable and even causing volcanic erruptions) are all pretty neat and nicely based off Aztec and Mayan mythology (and the Mayan calendar). Further detail is given to some Wonders and mystical locations (including the Andes). Pretty cool.
The next chapter focuses on classical Greece and Rome and their continuing influence on western magic. Everything from Plato to Greek mythology to Roman Hermeticism to "enlightened science" is explored. Its pretty cool if you want to incorporate Greco-Roman magic into your games. This section also has a lot of plot seeds, such as the start of the Ascension War, the "Golden Race" and the Oracle of Delphi, so player's might want to skip this. Some decent rotes, Wonders and mystical locations are given, along with some classic monsters. Pretty neat.
The closing chapter covered the magic of the Inuit and other people of the Arctic Circle. It was pretty decent, going into great details about shamanism and hunting magic in the far north. The rotes, Wonders and spirits given are all very good, and can easily be adapted into almost any shamanic paradigm. Over all, this was an excellent book. I would recommend that if you intend to use any of the cultures in here, you look through both "Guide to the Traditions" and any number of books on history, archaeology, mythology and/or anthropology as well. I already found quite a bit of the African, Aztec/Mayan/Incan and Inuit sections helpful for running all Dreamspeaker chronicles, and intend to use the Mesopotamia stuff in a "Year of the Scarab" centered game. I'm certain other STs will find this book equally useful.