From the back cover:
It's your weekly HackMaster game, and your players have trumped every trick you have thrown at them. What's a clever GM like you supposed to do? Grab your trusty Hacklopedia Field Manual! This book is for GMs out there in the trenches, facing arrogant players who think they can handle anything. Rock your players back on their heels when a "routine" encounter with an Ape Shaman takes a new twist -- this is actually a Blood Ape Shaman, a rare (and deadly) variant! Slip a few more tricks up your sleeve at the gaming table each week with the Venusian variant of the Giant Land Squid or the Chameloid Flesh-Eating Zombie!
Your players won't know what hit 'em!
Collected in this volume are hundreds of twisted new variant creatures as well as classic monsters from all eight volumes of the wildly popular Hacklopedia of Beasts. These ready-to-hack variants have been modified as described in the Hacklopedia of Beasts: Monster Matrix. Before you surprise your players with your carefully crafted Elder Mottled Green Lilliputian Red Dragon, see how those variations apply to other beasts. When you are ready for an even greater challenge, add supernatural abilities or element/climate changes to an already tough creature, such as a Subterranean Draco-Cockatrice.
Are you new to HackMaster? Well then, this is a great starting book for you! Selecting classics from the pool of over 1,700 monsters in the Hacklopedia of Beasts, the Hacklopedia Field Manual provides a variety of HackFactors for every encounter level. Threshold of Pain and Fatigue Factor information is provided in every statistic block, as well. Variant changes are clearly described in each entry, allowing alert GameMasters to run standard or variant beasts from this one book. Whether you are a new HackMaster GM sitting at a table with seasoned players who think they've seen it all, or an experienced GameMaster looking to spice up the game, the Hacklopedia Field Manual is an essential resource for your arsenal!