Balancing Encounters like in Rules Cyclopedia

I understand the motivation of ACKS regarding not leveling the encounters for the party but just making coherent dungeons and leveling the dungeon levels (how many times I said “level”?)

However, I like the idea of knowing in advance if a encounter will he hard or easy for the party, as I don’t want to kill them if they are in a good track. Mostly for adventures that are not “going to a dungeon and get the treasure” but missions. I don’t want to send them to a death trap just because I don’t know. I want to know and then do whatever I want.

I found some comments regarding this in the Rules Cyclopedia (pages 100 and 101) and I like the way it’s put.

In a nutshell:

  1. Determine the TPL (Total Party Level) of the PC party
  • SUM of all the character levels
  • For every hit points of damage, reduce 1 level. e.g. Fighter lvl 8 will reduce 1 level for every 8 hit points of damage.
  1. Determine the Individual Adjusted Hit Dice of the Monsters
  • SUM of all the HD
  • plus * and special abilities
  • minus the minuses
  1. Determine the type of challenge faced
  • Get the ratio between both levels.
  • if Monsters represent 20-30% is easy
  • if Monsters represent 30-50% is a good fight
  • if Monsters represent 50-70% is challenging
  • if Monsters represent 70-90% is major
  • if Monsters represent 90-110% is risky
  • if Monsters represent 110+% is Extremely dangerous

I’d like to know if it makes sense for ACKS numbers-wise as I’ll intent to use it.


I personally am not a fan of systems like this. RPGs tend to have too many intransitive relationships for a mechanical balancing mechanism to function.

That said, if you want to try:

  1. ACKS characters are somewhat more powerful than Rules Cyclopedia characters. The ability of fighters to cleave through the opposition means that, e.g., 5 orcs are much less of a threat to a 5th level fighter than in Rules Cyclopedia. The ability of mages to freecast their desired spells is a nice buff. You need to calculate most characters as being at +1 level, and mages and elves at being +2 levels above their HD for purposes of encounter effectiveness.

  2. Insofar as you introduce antagonists who can “alpha strike”, the system can be readily broken. Consider a party of 9th 1st level characters (TPL 9) encountering a single 1st level mage with Sleep (adjusted HD 1/2++=2.5). This would be a 27% ratio, or “easy”. But if the mage gets his spell off, he has a 50%+ chance of wiping out the party… Which is extremely dangerous.

  3. Because of the discontinuity in the power curve at 1st level and 9th level, the system works best when parties of 3rd to 8th level characters confront non-character monsters.

Example: Marcus (F5), Quintus (M5), Daphne (ES4), and Balbus (C5) confront a group of 4 Ogres (4+1 HD). The party’s TPL is (5+1 + 5+2 + 4+2 + 5+1) 25 versus (4 x 4.25) 17. 17/25 = 68%, it will be a challenging fight.

[Ninja’d by Alex, sort of … I wrote the following earlier today after reading this thread on my phone.]

You might find the RC approach helpful as a “rule of thumb”, however …

“Challenge Level” or “XP Budget” approaches to encounter design by their nature are built on assumptions which may or may not be applicable to your game. Being aware of these assumptions can help gauge how useful a particular tool may be. Unfortunately, I don’t know the RC’s assumptions.

3E has the most well-documented set of assumptions: “balanced” Character Levels between Classes, a specified number of encounters per level gained, and a specified assumption of Character Wealth by Level, with an implied allocation of that wealth to magic items. That’s really a lot of assumptions, which is one reason why Challenge Level is often criticized (even though it can work for 3E within its vary narrow constraints).

At this point, I’d recommend Googling Tavis and others’ posts on D&D as sport versus D&D as combat/war.

Both approaches have their place. A Godzilla vs Bambi style TPK with first-time role-players may not lead to more role-playing. One of these days … I’d like to run a Gladiatorial campaign (“5000 Quatloos on the Newcomer!”) featuring “D&D as sport” within a “D&D as war” world.

Don’t underestimate your players – if you’re new to BX/ACKS play, try out the guidelines you found with the level of challenge you’re looking for in some initial “kick-off” encounters. (Starting off a campaign with “Roll Initiative!” can be fun.) I bet your players kick ass. Stock a dungeon using ACKS’ guidelines (or use a free or commercially-produced OSR “module”). If your PCs are 1st level, you may lose some or even all. But ACKS is surprisingly survivable – it’s as likely your PCs will be scarred in some way and learn the value of reconnaissance and retreat, stealth and tactics.

In early levels I find that the rough breakdown of total HD of the monsters versus the total HD of the players in one encounter is not far off from what can be earmarked as a “challenging” encounter. Generally a little bit of experince tells you when an asterix or magic ability will throw things off. (Like the sleep spell mentioned)

I’m kinda shocked that the RC had the challenge level breakdown in there as Basic is particularly swingy depending on magic items and plain variety of PC/monster abilities.

Also, I you are plotting it out, I would default to plain “underpowered” encounters for the first couple of adventures, that way you can avoid killing PCs too easily and get a gist for their capabilities and better judge how to challange them.

I find player’s don’t get as bored with easier opponents in B/X as they do with 3.5 because the mechanics of the system go faster when they are winning and it doesn’t feel quite like a grind.

Hey! Thanks for your comments! I’ll try your suggestions and see how they go.