From the back of the book:
A definitive d20 System resource for enhancing and modifying the monsters. The book includes:
More than 60 new feats for monsters of all types.
More than a dozen new prestige classes, including the thunder hammer giant and draconic tyrant.
Dozens of new special attacks, special qualities, and traits conveniently broken down by creature type.
New templates such as the chaos dragon and relentless undead that can be applied to a variety of creatures to create devastating and interesting new breeds of enemy.
Detailed guidelines on adding abilities to monsters and adjusting their CRs to reflect the new challenge for PCs.
A comprehensive discussion on using monsters effectively in your game, and suggestions on how to modify existing monsters to present exciting and mysterious new challenges to your players every session.
In-depth suggestions for combining core feats, skills, classes, and magic items with different types of monsters.
Sample creatures in each section showcase the new rules and make suggestions on how to effectively integrate them into your campaign.