The Galdrabok is split into two parts: a history of ancient (particularly Icelandic) magick and a variety of Icelandic and Teutonic magick spells.Flowers historical account is interesting even if you do not believe in the existance of magick. This account is particularly interesting if you are researching this topic; I have not seen too many books that go as in-depth as Flowers does. Flowers also includes one or two sets of runes for those interested.
For those interested in the applications of the spells, Flowers includes an extensive list (and how to work the spell) for everything from staunching blood (this one actually works) to good luck charms. He informs the reader as to what materials are required, as well as what the characters (called "staves") should look like. Flowers also includes an extensive bibliography for those wanting more information on the subject.
As with most books on magick, Flowers suggests that you be careful, but not in a "standard" way. Rather, Flowers tells of one overly-eager magician who hungered for more and more powere - he was destroyed by that which he sought.
WARNING: Some of the material in this book is NOT SUITABLE for children.