[The following review is based on the hardcover edition. I own several Paizo softcover "pocket editions" and I've found them a durable, economical, and lightweight alternative to the hardcovers.]
------------------------------
Published back in 2009, the GameMastery Guide was one of the early hardcover books released for Pathfinder. I think it's an overlooked gem, as I crack it open before and during sessions as often as any book other than the Core Rulebook. Weighing in at a hefty 320 pages, the GameMastery Guide has advice on the usual topics that new GMs need help with, but it also contains so much more, like little new rules subsystems, a gallery of pre-made NPCs, all sorts of random tables, tracking sheets, etc. It's a very handy compilation of material specifically designed for Pathfinder, and I'd recommend it as an early purchase for any GM getting into the game.
We have to start with a shout-out to that awesome cover, featuring Runelord Karzoug seated on his throne. I'm partial, since I'm running a certain AP at the moment, but artist Wayne Reynolds knocked it out of the park there. There's no way the interior artwork could be as good, and it's true that many of the interstitial drawings are recycled from other products or are forgettable placeholders. However, the artwork accompanying the NPC gallery is solid and fits the feel of Golarion. If I were using letter ratings, the cover art would get an A+ and the interior art and layout would get a C+.
The book is divided into 9 chapters, with multiple appendices and indices.
Chapter 1, "Getting Started", is stuff that experienced GMs will have seen a thousand times before, but that new GMs will appreciate. It covers stuff like a gaming glossary, how to deal with sensitive topics, how to find players and set aside a place to play, developing house rules, etc. It's standard advice, and if I had to quibble with anything it's that the section is so focussed on catering to players' desires that it leaves out a crucial consideration: the GM needs to have fun too! I did like the idea of creating a custom player's guide before each new campaign, and that's something I'll probably do in the future.
Chapter 2, "Running the Game", talks about preparation, presentation (music, handouts, lighting, etc.), building encounters and adventures, and how to handle in-game problems (PCs missing a clue, getting too much treasure, etc.). Again, it's all solid advice (though I don't agree with customising encounters for PC abilities, as that holds the risk of undermining the very advantages they've worked to gain). I think the best bit in the chapter is the "Game Changers" section, with talks about how to handle problems specific to Pathfinder: spells involving invisibility, teleportation, lie/evil detection, flying, auguries, and more. These spells can dramatically change the game and wreck certain types of plots if a GM isn't careful. The section ends with some good tables: fifty different adventure plots, twenty plot twists, and a bunch of macguffins. Good material if you're creating your own adventures and get stuck in the brainstorming.
Chapter 3, "Player Characters," talks about handling metagaming, introducing new players into the game, handling treasure and character death, whether to allow evil PCs, and different types of common players like the "One-Trick Pony" and the "Rules Lawyer". It's a good and useful discussion, as experienced GMs will encounter these various player types sooner or later and knowing what to look out for and handle them is important if groups are going to persist in the long-run. I think what the chapter is missing is the frank advice that some players just aren't right for some groups, some groups are dysfunctional and need to disband, and that the GM (unfortunately) often has to make the hard calls. It's a responsibility that goes beyond preparing and running adventures, since real people, real relationships, and real emotions can be involved. I'd rank the chapter as average.
Chapter 4, "Nonplayer Characters," goes into the basics of giving NPCs personalities and roles in the game. I especially liked the section on traps a GM needs to avoid when running NPCs (such as making them too intrusive, too decisive, too good at combat, etc.). The section introduces a new concept of "NPC Boons," which are special little plot or mechanical advantages that NPCs of different types can give to PCs. We'll see this concept more in the NPC Gallery at the end of the book, but the idea would be that, for example, befriending a local tracker would give the PCs a +2 on Survival checks in the area for one month, or that buying a drink for a down-on-his-luck nobleman could result in a primer on local politics and a +2 bonus on Knowledge (nobility) in the city. Etc. It's a nice way to quantify and reward PCs for good role-playing and encourage those players who are only in it for the bottom line to have more patience with what may at first seem like irrelevant asides. After some fairly mundane advice on villains, the chapter concludes with a great collection of tables: NPC backgrounds, goals, physical characteristics, personality characteristics (some of these are hilarious and memorable, and I wish players were as creative!), occupations, secrets and rewards, and even the surely-delightful "Random Adventuring Party Name Generator". If you want to be cool, join the "Reputable Pearly Kraken Monster-Slayers in the Shadow of Angels"!
Chapter 5, "Rewards," contains an insightful discussion of why rewards manner and the different ways they can be conceptualised and allocated. It goes through the difference between steady small rewards versus occasional big ones, intrinsic vs. extrinsic rewards, and how different players value different things (e.g., is it all about the gold, or is getting on a first-name basis with the barmaid better?). It even gets into little details, such as exactly when XP can be awarded (I forget that some groups do it after every single encounter, while others only do it during true in-game downtime). There's some good advice on how to handle spell research and magic item crafting that makes it clear the whole process needs to be treated more as an art than a mechanical formula. This chapter has a *lot* of random item and random magic item tables, which is really useful when you need to see what a little shop in a small town happens to have in stock, or what that NPC wizard you weren't expecting the PCs to rob from has in his satchel.
Chapter 6, "Creating a World," is for GMs who do something I've never really done in Pathfinder (though I have in science fiction settings): create a brand new campaign setting. It has a nice process of answering a set list of questions to gradually firm up the details of the new world and to simplify (to some degree) the difficulty of conceptualising everything all at once. The geography advice is probably over-ambitious, but the concepts are explained really well. The chapter goes through different types of societies and different technological levels. It's not a chapter I'll use, but it's very good for homebrew GMs.
Chapter 7, "Adventures," has tips for running stories in different environments (dungeons, the wilderness, etc.). It has particularly good advice on dungeons, with a useful key to map symbols that I should use more often. Again, there's a ton of great tables to stimulate creativity, including random tables on where dungeons can be found, what type they are, what's in different rooms, and several random monster encounter tables (which I wouldn't actually roll on, as they have the common problem of spreading CRs from as low as 1 to as high as 13 in the same table!). The chapter has a section on planes and planar traits, which is an important reference for later products that make specific use of the mechanics presented here. Similarly, it has a section on stat blocks for settlements (used in most Pathfinder products) that is quite important in determining what's for sale in a community, the highest-level of spellcaster available, etc. I use the settlement rules a lot, and although I think they're sometimes a bit cumbersome in play, they're important in making sure that a hamlet "acts" differently than a metropolis. This chapter is packed with a lot of other material, including a two-page rules-set for ship combat (it seems worth trying), lots of random tables for ships and sailors, and, one of my favourite things, random tables for tavern names and unique traits. There's a lot here that I'm going to photocopy and keep with my GM screen to help me quickly come up with more flavourful interludes when I'm running games.
Chapter 8, "Advanced Topics," introduces several new little rules sub-systems: chases (elegant, but not completely satisfying), natural disasters, drugs and addiction (happens too quickly and needs a slower progression of effects), fortune-telling (too general), gambling (done well), haunts (one of the best innovations of Pathfinder, great for story-telling), hazards (mostly supernatural ones, but very clever), and sanity/madness (too simplistic, but not bad for just 2 pages). Some of these sub-systems, like chases and haunts, are seen in a lot of other Paizo products, so having the rules on how to run them is really useful. Other topics touched on in this chapter have been developed in far more detail elsewhere, and may be of more limited usefulness. Still, there's enough of enduring value to make the material here worth reading.
Chapter 9, "NPC Gallery", is one of those things every Pathfinder GM needs: full stats (and even pictures and descriptions) for NPCs encountered on short notice: bandits to spice up overland travel, city guards for when the "Chaotic Stupid" PC gets too obnoxious, the bard intended purely as tavern-dressing that the PCs are surprisingly interested in, the shopkeep they want to try to bluff for a discount, etc. There are dozens and dozens of great NPCs here, both low-level "townsfolk" and high-level threats, and all are fully fleshed out with gear and boons (from Chapter 4). In addition, there's really good advice on how to swap out a feat here or a weapon there to create different variations on the stock NPC. I've used this chapter a lot (as have many PFS scenarios). The later publication of the NPC Codex and Villains Codex makes this section slightly less crucial, but I still get a lot of use out of it.
Apart from indices and an appendix (on recommend reading and films), the book ends with a miscellany of tracking sheets--a Campaign Sheet, a Settlement Sheet (something I should actually use, now that I think of it), an NPC Sheet, and a Basic Rules Cheat Sheet (that I'm going to start handing out to new players to ease their transition into the game).
From the chapter summaries above, you can tell the book is just chock-full of useful advice and resources for running the game. Although essential for new GMs, even experienced ones will still find a lot here to make the book worth buying and reading.
