From the back of the book:
"Epic Monsters. The name really does say it all.
This tome is the perfect resource for games masters whose campaigns are nearing epic levels of play and need additional support to take their campaign beyond 20th level. With a veritable plethora of tremendously powerful creatures detailed within, Epic Monsters is the definitive source of challenges for the emerging epic level campaign.
In these pages lurk a huge collection of unique, epic and near epic level monsters to challenge your party with. In addition to the 150+ monsters packed inside, we have included an appendix of epic level antagonists. Immortals, the Lord of the Infernum, and Bodiless Ao (from the final chapter of the acclaimed Drow War series) all make an appearance in this section.
There is also a comprehensive list of epic level feats for use in your game, including additional standard feats possessed by monsters within this book and old feats updated to expand them beyond normal levels.
Welcome to the third volume of the Expert Player's Guide series - Epic Monsters!"