Probably the best thing I bought this GM's day. Book of Battle is a complete and comprehensive guide to running large scale abstract cinematic battles in which the PC's participate by taking a minor but ultimately decisive role in the battle. The rules are highly focused on Pendragon, but could be used as inpiration for handling battles in a similar way in just about any system (albiet with a consider amount of work and strong knowledge of rules smithing).

Without having playtested the rules, they seem well considered. Though keep in mind, this is the fundamentally this is using the same underlying system as classic Call of Cthulhu with all the lethality that implies. Things in this system can go bad in a hurry.

There are a couple of things to understand about what this book is offering if you are to be happy with your purchase. First, it's a ground eye view of the battle. While the PC's participate in the battle, they do from the in character vantage point and not with the god's eye view and total control of wargame commanders. This has advantages and disadvantages. The disadvantage is obvious, in that players have relatively limited control over the situation and this might not be ideal for some games where the act of being the commander and manuevering armies is the aesthetic pleasure you are going for. The advantage though is that you can run a mass combat as if it was a normal tactical skirmish using the normal combat rules of the system with only minor adjustments based on a calculation of the circumstances the battle is simulated - out numbered, favorable or unfavorable terrain, etc.

Secondly, related to the prior design choice is that the battle is abstract and the majority of the narration of the battle will come not through the process of play but out of the imagination of the GM. GMs will need to decide the local circumstances of the battle, what the PCs can see from there vantage point and how the larger battle is going. A full simulation of all the events of the battle and what is happening to each and every NPC is beyond the scope or intentions of the system. This of course lets the system be faster and more wieldy, but comes at the expense of granularity and relies heavily on the GM having a great imagination and some idea of spatial awareness and story telling skill, to weave together a whole fight just from the vantage point provided by the game.

Thirdly, this system is intended for large battlles, and I do want to put an emphasis on large. The game system states outright that is not intended to simulate battles with less than 1000 total combatants. I'm not entirely clear on why this is so. I recognize the intention is to abstract the battle out to being so large that the battle system is disconnected completely from the normal combat system, but I feel that above say 200 combatants there is enough going on in a battle that it's all the same whether it's 200, 2000, or 200,000. It's just already abstractly "big". Perhaps there is another system meant to cover fights of 25-1000 combatants, but I don't immediately see the logic here. In any event, if your intention is to use the system for fights of less than 1000 total combatants, then you should either look somewhere else or else you are on your own as to how to adapt this system to that circumstances.

Overall I consider this an excellent and very functional attempt to provide a mass combat minigame. I don't believe any RPG system is complete without putting a mass combat minigame in the tool chest of the GM, and obviously in a game like Pendragon with its hard commitment to simulation of a knightly world this is doubly true. The rules provide an excellent balance between simplicity and simulation and if the oppurtunity comes up I would totally enjoy using them from either side of the screen.

Four stars rather than five only because the utility here is narrow to particular intentions and aesthetics of play. This is not going to serve every GM's purpose in every scenario. Every mass combat system is going to make compromises and so that's no ones fault, but what it does mean is if you want a complete system you are inevitably going to be buying another book or aid. But for what it does I think it does a good job.

This is a VERY complex system. That in itself does not make me hate this pdf so much. Note that I refer to the pdf and not the book. The pdf is completely devoid of an interactive table of contents. This is insane. The system is so complex that it necessitates referring back and forth through book during the course of a battle and without an itemized and hot linked table of contents it's almost impossible to run a streamlined battle. This is not the only problem, by far. The tutorial for the opening battle of the GPC (Great Pendragon Campaign) is incredibly flawed. It directs the players and to refer to specific tables and rules throughout the book. This would be bad enough without the table of contents, however, many of the referrals actually specify no page numbers, so good luck running an interesting first battle. The example tables are also inconsistently presented and either insufficiently or incorrectly filled out. I actually like this system, it provides a sufficiently diverse and "realistic" abstraction of what I imagine a medieval battle would consist of. It's not the system that is at fault, it's the awkward and seemingly unfinished layout. If you want to learn to run a good battle, do NOT read the whole book and then run through the tutorial with your player knights, as the book suggests. Your players will likely lose interest in running a battle ever again, unless they're saints, or make their Merciful checks. Read the book through several times and then roll up some bare-bones NPCs (with just their relevant combat skills, stats and derived stats) and run them through a few of your own battles at a slow pace, as if they were player knights. It's going to feel like studying for exams from a badly edited chemistry textbook from the 1980s, because really, it is.