At some point in their career, every GM will inevitably run a mass combat. Maybe it’s all part of the campaign’s grand design – ‘the war to end all wars’; Maybe the battling hordes were supposed to be merely background description for the PCs’ mission and a few bad dice rolls put them in the middle of the jackpot; Maybe the Party kicked the proverbial hornet’s nest and was forced to “call the banners”. Whatever the case, refereeing both the Party’s combat, and the overall battle as a whole can be quite difficult to pull off smoothly.
The potential drawbacks are many. In the worst case scenario, you’ll be managing initiatives, hit points and dice rolls for groups of allies and enemies after having been forced to look up your game system’s rules for converting a single monster into a platoon of creatures – which doesn’t even touch on unit morale, commander bonuses or… you know, your players. Those people who got bored waiting for their turns to come back around and drifted off to a youtube video on their phones.
Long story short, most pen and paper RPGs simply don’t manage mass combat very well. Either the system is overly complex, with too much to effectively track while also running an encounter for the players, or so abstract that you’re just sort of making it up as you go anyway – which kind of begs the question as to why you bothered to look up the system in the first place.
There is another medium you can use, one that tends to be designed around managing battles between groups of minions: Collectable Card Games.
Before I go any further, No, I am not suggesting you break out the Magic cards mid-session and use them to be your mass combat. What I am suggesting is you consider some of the mechanics that card games use to more quickly manage NPC actions without having to make everything up yourself. In most cases, you’ll find that CCG cards have the same sorts of things that your NPCs do – things like hit points, attack values and magic effects.
The format that CCGs use tends to be simpler than RPGs however, which works out great for you the GM. It becomes far easier to determine the outcome of events on the battlefield when the method for determination is streamlined (and round-based, just like your RPG). It also keeps you from being bogged down in rulebooks. Consider the following scenario:
The besieged human commander issues orders from behind the walls of his fort, with squadrons of archers manning the towers. The PCs must circle behind the horde of orcs with the commander’s cavalry and break through the enemy reserves to strike at the greenskin warchief before the fort falls. Do they make it in time? How does the battle play out?
For simplicity’s sake, we’ll look at just one side of this setup, the fort battle taking place while the PCs are racing off to fight the warchief. If I know that the “walls” are zero (0) attack, eight (8) health creatures, “archers” are one (1) attack, one (1) health creatures that can “tap” to do one (1) ranged damage and cannot be targeted by melee creatures until the walls are destroyed, this puts the defenses into a mathematical form that’s easy to work with.
Now suppose our orcs are of two varieties, one (1) attack, two (2) health “brutes” and one (1) attack, one (1) health “grenadiers” who “tap” to do one (1) ranged damage to a creature, or two (2) ranged damage to a wall.
With this established, determining how the battle plays out – and how long it takes do to so – becomes basic math and target choice. If the defense is four (4) walls, and eight (8) archers, figuring out how long a battle takes between them and nine (9) brutes, with twelve (12) grenadiers is fairly easy to do on the fly. Determine which side goes first, and play out round by round making choices and describing the outcome – all while tracking a fairly small amount of information.
Obviously, the above example of only half of what we would need to do for our scenario: the other half being sorting out the cavalry and the orc defenses to get through while the PCs make their attack… BUT, it’s also only the tip of the proverbial iceberg. There are tons of card games out there with huge numbers of options to explore and cannibalize for ideas. The important thing to note is that you can do all of this mass combat without seriously impacting your ability to run a normal combat encounter for the players.
Finally, let’s not forget that all important fluidity factor. You can customize this process as much as you want, and adapt to things you weren’t counting on with relative ease. What’s that? the Party just summoned a huge earth elemental to aid their infantry units while they go off to battle the trio of ogres? No problem, that two (2) attack, ten (10) health bad boy is gonna mess up some brutes before he goes down. That meteor swarm the Party’s wizard just cast? Easy, divide twenty (20) damage amongst the creatures in the area, or fifty (50), it’s your game.
The bottom line is, the statistics of the creatures involved in mass combat only becomes relevant when the players confront them directly. Until then, it really doesn’t matter that you’re using entirely different rules to operate them. All that matters is that there is an underlying structure that lends consistency and credibility to the process. Since you’re borrowing from a medium that has both in place already, it’s going to be easier to conduct mass combats that feel right to your players, keep the game moving, and are mechanically sound.