The short story here is that the M&M Gamemaster’s Guide is close to indispensable for M&M GMs, and large parts of it are very useful for GMs running other superhero systems. The long story follows, from the perspective of a GM in the latter group.
Chapter 1 takes a good long look at various potential campaign settings, using the “metal ages” trope common in comics: Golden Age, Silver Age, and so on up through the (not-yet-metallic) Modern Age. After this, various origin types (aliens, gods, mystics, mutants, etc.) are surveyed, followed by an excellent and engaging discussion of how super-powers and super-powered individuals might fit (or misfit) into a modern society. Both of the foregoing sections, especially the ones on origins and powers, are excellent resources not just for GMs, but for players as well. The cosmology section that follows helps GMs think through issues like alien worlds, parallel Earths, and so forth. The “History” section perhaps could have been better placed right after the “metallic ages” discussion, for it guides GMs through the process of considering the place of super-powered individuals in the world prior to the campaign’s present (and even into the campaign’s future, if time travel works in the GM’s universe). The penultimate section in chapter 1 also revisits and extends some material from earlier in the chapter, discussing such issues as the legal status of superheroes, their standing to make arrests, and even the existence and role of comic books in your super-powered setting. Finally, chapter 1 turns to organizations of various sorts, with advice about the characteristics and even naming conventions of typical organizations in a comic-book world. Except for a few weapons, there’s no M&M crunch in chapter 1; it’s a fun read for any comics fan or aspiring comics writer and a great resource for a GM running superheroic games in any system.
Chapter 2 turns to villains, a “necessary evil” in comic-book worlds. The discussion of villain “levels” is tied to M&M PLs, but the concepts can be adapted to any system. The good, though perhaps not entirely comprehensive, survey of villain “types” (typical actions), “roles” (relationships with heroes), and motivations is pure storyline, and will serve GMs well no matter what superhero system they’re running. The excellent section on villainous combat tactics obviously presupposes M&M3, but isn’t very “crunchy,” and could easily serve GMs running an earlier version of M&M or a completely different game. In particular, the subsection on “Singular Villains” addresses a common problem that even GMs running completely different genres might appreciate: the one-vs.-many setup of many superhero combats. I particularly liked the discussion of strategies for helping a villain escape from a losing battle, and I almost think that the subsection on “Why the Villain Loses” should be required reading for all GMs running superhero games. Similarly, the sections on “In-Depth Villains,” villain teams (like the Injustice League or the Masters of Evil), and villainous organizations (like Hydra) will help any GM flesh out a superheroic world.
Chapter 3 includes a lot of great M&M3 crunch. It starts with a helpful discussion of the ways in which villain creation differs from hero creation (for example, a villain’s PL is a result of the villain’s design, rather than a constraint on it). In the “Powers” subsection, the discussion of “stunned power capabilities” is short but critical. Paying attention to the advice, especially the mechanical (system crunch) notes, throughout the whole chapter can help save you a lot of time while preparing villains. Naturally, using the archetypes provided in this chapter (including the archetypes for minion, including nonhuman minions like dinosaurs and robots) can save you even more time.
Chapter 4 provides inspiration for villainous plots (as in “schemes,” not necessarily as in “storylines,” though these overlap to a significant degree. This chapter analyzes five basic super-villain plots—conquest, destruction, kidnapping, murder, and theft—breaking each one down into its various component parts, with plenty of attention to possible variations. A second substantial section on “Adventure Elements” offers various ideas for generic plot hooks and plot elements, such as using heroes’ own powers as focal points for adventures. There’s even a table of 100 adventure seeds that a GM can use to select an adventure seed randomly.
Chapter 5 begins with a section on disasters, supplementing the environmental challenges presented in chapter 8 of the M&M Hero’s Handbook. The second section deals with traps that villains might use to detain or even kill superheroes.
Finally, chapter 6 includes a bunch of rules options, including power point budget variants, custom-built fighting styles, reputation, knockback, and mass combat.
An appendix includes nine ready-made villainous lairs.
Every feature of the Gamemaster’s Guide is top-notch, aside from a few misspellings and grammatical errors. Well over half of the book is useful for GMs running any superhero system. The artwork, too, is excellent and really enhances the book. The PDF version includes a complete set of bookmarks. This volume is a fine addition to any GM’s library.