Designing Encounters for the OSR: The Myth of the "Balanced" Encounter

 I have habit of saying that in Dungeons and Dragons 5e, a balanced encounter is one in which the monsters are defeated before anyone in the party dies. In the OSR space, a balanced encounter is one in which the monsters are defeated before everyone in the party dies.

That is, in OSR a fight between a 1st level fighter and an orc is a pretty even match. Put up 5 first level fighters against 5 orcs, and it is a coin toss who the last man standing will be. If you want to manipulate the odds so that there is a high probability that all the orcs will be killed before any of the fighters, (say, five fighters against one orc and the fighters somehow gain initiative) you haven't created a balanced encounter but rather one in which the fighters will mop the floor with the orcs.

For those who like math, is fairly easy to calculate what kind of ratio you need to balance an encounter. First it is the average damage done by each combatant on a successful hit (a d6 weapon does 3.5 points damage per round for this purpose. D8 does 4.5. D10 does 5.5, and d4 does 2.5). You would add any damage modifiers to this, such as a magical weapon or strength ability modifier for.

This damage is multiplied by the % chance to hit. Say a 1st level fighter needs a 16 to hit AC 17, that is a 25% chance to hit. (The fighter hits on a 16, 17, 18, 19, or 20, or 5 out of 20 odds. 5 is 1/4 of 20, or 25%). So multiply the fighter's 4.5 points damage per round by 20% and you get .9 points damage per round. Do this for each combatant to get the average total party damage per round, then do the same for the opponents. Compare total hit points of each side and you'll get an idea of how many rounds it will take for one side to eliminate the other.

The question is, is this a useful way to design an encounter? Do you want to create a likely TPK every time your players get in a fight? Is there any reason to actually create a "balanced" encounter? If the likely hood of killing most of the party members is high, you might as well throw overwhelming force at them and not worry about balance. If you want them to have a fun tough fight, then you just need to total up the levels of each side and make sure that the party's total levels are double or triple the total levels of the monsters.

Much more important than worrying about creating "balanced" encounters is designing encounters in such a way that players have the ability to size up the difficulty of a potential fight so they know whether to engage or to find another approach. (Run away, diplomacy, stealth, surprise, etc...). Some of this the experienced player will know intuitively. If they are a party of five 1st level characters, and they are facing a party of 20 1st level monsters, the odds are not in their favor. But if we want to take meta-gaming out of it, there can be other signals as to encounter difficulty.

A monster with trophies outside its lair of the opponents they defeated is one example. This could be shields with coats of arms, bodies or parts of bodies (heads or skulls for instance), or weapons (for the arrogant monster daring any challengers to take up arms against it). It could be a display of power (casting a spell, a breath weapon, crushing a stone easily, firing a powerful warning shot, etc... It could also be information gathered or revealed via rumor, eye witnesses, journals, or other records.

This is where folklore and myth come into play. It is also a potential for the party to discover a key element of the monster's weakness. They may know about vampires and werewolves, but only Bilbo Baggins knew about Smaug's weak spot on his underside. This information was overheard by a thrush, who flew to Laketown and revealed it to Bard the Bowman so he knew that only the Black Arrow would aim true enough to hit the one vulnerable spot.

And here is the crux of encounter design. Information trumps power. Van Helsing (the book character, not the movie version) does not defeat Dracula because he is more powerful than him. He defeats Dracula because he understand both the vampire's power and weakness. There is no "balanced" fight between the two of them. At night Van Helsing wouldn't stand a chance. But during the day Dracula's only strength is in secrecy and faithful henchmen.

Edward Gorey