Designing the 13th Age GM’s Resource Book

13th Age GM Resource Book cover

Pre-Order the 13th Age Gamemaster Screen and Resource Book, and download the PDF now!

“We have targeted the game toward experienced gamemasters and players at all levels of roleplaying experience.” – 13th Age core book

13th Age assumes you already know how to run an F20 roleplaying game—in fact, you’ve probably already done it more than a few times. You’re comfortable customizing a game to fit your style of play, improvising adventures based on player input, being the final decision-maker on rules questions, building out a campaign setting based on a few cool ideas, and creating your own monsters.

As a result of this design approach, 13th Age sometimes asks more from GMs than other games. That’s why we’ve always tried to support 13th Age GMs by answering questions and supplying resources and guidance. A few months ago, we reached a point where we felt we knew enough about where our GMs needed a little extra help that we could write a solid GM’s guide for the game.

Using the Trail of Cthulhu Keeper’s Screen and Resource Book as our model, Cal Moore and I huddled with Rob Heinsoo and talked about what would be good to include in this slim volume (around 64 pages). Based on what GMs had been asking us over the years, what would be most useful?

We’d definitely need to talk more about icon relationship rolls, which were brand-new tech in the core book and have been relentlessly discussed, debated, tested, and tinkered with by 13th Age GMs and designers since then. We often see  questions about using terrain in combat, and Cal had lots of ideas he wanted to develop around that. His recent experience with the Battle Scenes books (still in development) gave him great insight that we could share about building better battles in the game.

13th Age GM Book NPC sampleThe Keeper’s Resource Book included NPCs, so I eagerly volunteered to create (statless) characters associated with the 13 icons that GMs could easily pop into their games as one-off encounters, recurring characters, or even major villains. I also wanted to revisit the subject of backgrounds, which I wrote about in a previous Page XX article.

ASH LAW had begun work on an ambitious toolkit for improvising adventures, but other priorities left it orphaned. I took it apart and rebuilt it into a lean, mean, GMing machine for running zero-preparation sessions of 13th Age. And hey, speaking of ASH, we decided that it was finally time to make her Montage mechanic from Organized Play an official part of the rules. So from now on, when someone asks, “Where are Montages described?” the answer is, “In the GM’s Resource Book”.

We also recruited Rob to write a section called “Six Things Rob Does Now”, and compiled general-purpose GM advice scattered across various books.

We hope you like it, and we hope you get a kick out of the accompanying GM screen, which features freakin’ gorgeous new player-facing art from Lee Moyer and Aaron McConnell, and GM-facing quick-reference rules chosen with input from our community. (There’s also a map of the Dragon Empire, this time with the roads included. Huzzah.)


13th Age combines the best parts of traditional d20-rolling fantasy gaming with new story-focused rules, designed so you can run the kind of game you most want to play with your group. Created by Rob Heinsoo and Jonathan Tweet, 13th Age gives you all the tools you need to make unique characters who are immediately embedded in the setting in important ways; quickly prepare adventures based on the PCs’ backgrounds and goals; create your own monsters; fight exciting battles; and focus on what’s always been cool and fun about fantasy adventure gaming. Purchase 13th Age in print and PDF at the Pelgrane Shop.

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