"I am desirous of presenting creatures by region (or plane, subterranean, and similar categorical means) so as to make the work serve as a reasonable random encounter reference as well." (Dragon #103, November 1985)I'm not sure about the idea of breaking monsters down into such small boxes (arctic, underground, mountain-dwellers, etc.), because I think that would fragment things just too much and make the book unusable as a reference, for all of Gygax's good intentions regarding making it a random encounter tool. However, my recent experience with the Castle of the Mad Archmage has led me to conclude that some level of differentiation between creature types wouldn't be out of order, especially when you consider that beasties from the Monster Manual, Fiend Folio, and Monster Manual II (as well as some new ones) will all be included together. That leads me to consider the following as a useful, and not overly granular, breakdown:
- Wilderness and Dungeon Monsters
- Underwater and Waterborne Monsters
- Prehistoric Monsters (which would naturally include all those dinosaurs)
- Extra-planar Monsters
I break out extra-planar monsters because they, more than anything else, are unique unto themselves. I had thought about breaking out undead, but I think a comprehensive undead encounter table will fulfill that function (I'm planning on moving the random encounter tables to this book, and there will be a comprehensive index into the bargain).