The second in the Slayer's series of d20 sourcebooks by Mongoose Publishing, this book focuses on the gnoll. The book provides the GM with a description of what the gnoll looks like, how powerful these senses are, in this case, very good smelling and hearing abilities, and what they eat. While they can eat just about anything, they enjoy eating humanoids.

There are details on how long the gnolls live, how quickly they breed, and how their society is ruled. Since they are primarily chaotic evil, it's generally through strength of arms. Those looking for information on where the gnolls live, and how they live, will find brief information on each topic. Gnolls tend to live in tunnels and burrows using slave labor that quickly dies off either after poor treatment or being devoured.

There is very little information on some important subjects like religion though. Much like the Slayer's Guide to Hobgoblins, the information is rushed over with a nod to the official demon lord of the gnolls (that's Yeenoghu to you, buddy!) and some details about how they follow the cycles of the moon with reverence.

For those looking for a little more help and ideas on how to use gnolls in their game, the section, Scenario, Hooks and Ideas, has several adventure seeds. The section, gnolls as player characters lists the gaming information for using gnolls in the game. Edendale shows how the remains of a village destroyed by gnolls and the nearby burrows that host Eenoga and his pack. For those looking for a quick reference, there are several generic gnolls with stats for a 6th level fighter pack leader, a 4th level cleric, and a 3rd level pack leader, as well as standard warriors and the young.

To help add flavor to the book, there are several stories of the groups of adventurers encountering gnolls. Strangely enough, one of these encounters has little to do with gnolls as the gnolls appear and are killed outright by a fireball. Why is this piece of fiction here? To show how easily gnolls are killed by powerful magic?

The book also suffers from a dearth of crunchy bits. No famous gnolls, no famous magic items, no new spells, no new prestige classes or anything that can be inserted into any d20 game. Worse, when the game stats are finally revealed, they seem to be wrong. The gnoll racial traits include +2 to Strength and Constitution, with a -2 to Intelligence and Charisma. They have other abilities including racial bonuses to skills and armor class. The problem is that they are no modification to the character's starting level. With these high physical stats which have a direct effect on game play and the bonus armor class, these creatures should be a minimum of EL 1 if not 2. In addition, the gnolls favored class is Ranger, but the main pack leader, Eenoga, is a fighter, and the generic Dominant Male, is also a fighter. Fortunately, the generic gnoll pack leader is a ranger.

The layout is in standard two column format. Art ranges from great to okay. Mongoose does make good use of interior covers, using the front one for a gnoll close up, including the muscle and bone structure and a map of the ruined fort Edendale on the back cover.

On one hand, this Guide is a short if solid piece of information on gnolls. It has a lot of background material that can be put into any fantasy game, regardless of game system. On the other hand, it has so little gaming mechanics to add to your d20 gnolls, that unless your campaign is going to focus on these creatures for several adventures or your non-d20 fantasy game needs another race that you know little about, you might want to wait for an ecology article in Dragon Magazine, or the upcoming coverage gnolls are going to receive in the Chainmail rules.