From the introduction:
So what’s different about Dark Revelations Monsters?
While Dark Revelations uses a modified version of the current D20 OGL SRD mechanics, it is important to note that it is different than other D20 systems, and that D20 systems do change over time. Dark Revelations monsters where built using a combination of recognizable OGL sources, as well as our own reimagining of their powers and roles.
One of the things we found creating our own monsters in the current d20 context is that though many stats of a monster where nicely defined, the type and number of monster features a creature should have was hard to gauge. We found certain monsters where significantly less powerful than other monsters of the same CR, or hit dice.
Our redesigned monsters where developed to alleviate the problem that certain monster types became useless after a certain point, and to try to balance their powers as much as possible. Many of our monsters highlight the fact that all monster types should be used throughout the careers of the player characters.
So it’s just about the stats?
We make no apologies, we like our “crunch”, and our monsters and overall game system reflect that. Crunch can help even out using player knowledge against a monster in some cases; surely we want to get away from the old trope “this is only for GMs.” We want everyone to read our book!
But we freely admit, like all role playing games, there is some fudging here and there. It’s almost impossible to avoid without completely abandoning d20 all together, which is way too late to do for the current version. We cannot guarantee that all our statistical eye balling will be accurate or follow some nice mathematical formula. We can guarantee we did the best to we could to keep the numbers as aligned and as fair as possible, and to make each monster as balanced as possible compared to other monsters. We also will be honest about what we had to fudge.
Besides the joy of playing with concepts and numbers to see what we can create, we really wanted to build monsters that are unique to the world of Dark Revelations, and fit into its environment and story as much as possible. Thus all monsters have not only new stats, but new backgrounds. In many cases story or adventure hooks can be found in individual monsters, as well as new information on the world we are trying to populate. In many cases we tried to find ways to use monsters off the battle map in non-combat situations, and hopefully are just fun to read. Who doesn’t love a well fleshed out monster?