# Equation to generate Rolemaster combat tables results

Rolemaster combat tables present very different results depending on armor type and weapon, but are those results generated by some type of equation or algorithm? Maybe a different equation/algorithm for each weapon? I doubt they were generated by hand.

EDIT: I'll add some more information. For example, in Arm's Law page 11, the attack table for the broadsword is as follows:

The damage seems to follow some type of mathematical progression, always more damage when you get closer to 150, and the critical strike is also more dangerous. Critical strike type seems to follow, in this example, K-P-S-K order at first. I don't know, I was wondering if I could reduce the table to a mathematical expression.

Thanks!

• Comments are not for extended discussion; this conversation has been moved to chat. – mxyzplk Oct 19 '16 at 22:13

I've never seen any official statistics or formulas for the Rolemaster combat tables, if they did exist I'd be amazed if they gave them out as it would negate the need for Arms law. However the newer versions of Arms Law do streamline the process a little by grouping blocks of numbers.

In the classic Rolemaster Companion's there were several attempts to streamline the book system of RM to simplier single-page affairs.

Rolemaster Companion III (ICE #1700) presented a system where dice rolls were used and a modifier for armour was made; for example:

Make a d% open ended roll; add and subtract OB and DB as usual. Rolled dice are then used to generate damage and multiplied for a high roll.

Rolemaster Companion I (ICE #1500) has more of what you're looking for, although it's a bit intimidating. The Condensed Combat System attempts to recreate the tables with a formula system.

Take a seat and here we go...

1. Roll the attack, check for fumble/failure, modify by OB/DB and other factors as usual. This is the IAV.
2. Cross-index the attacks Table Type (Arms Law = AL) with the targets armour type in the Armour DB mod area, subtract this from the IAV. Then add the Weapon OB mod for the armour type. This is the FAN.
3. If the FAN is greater than the To Hit Threshold the attack does damage. Criticals result if it has passed the appropriate threshold.
4. To determine how many hits occured divide (FAN-THT) by the Basic Hit Factor (The number in brackets on the attack statistics area)

DAMAGE = ((OB-DB-ArmourMod+WeaponMod)-THT)/BHF

Let's try a worked example everyone!

Bob the Orc has a Falchion and an OB of 95, he attacks Eric the Thief who has a DB of 25 and is wearing chainmail (AT 13). Eric isn't parrying because he's been distracted by a malevolent moose.
Bob rolls a 50 to attack and the GM gets out his slide rule.

The Falchion has an OB mod of +4 vs chain and a BHF of 4.4.
AT 13 has a DB modifier of 15.
The THT for chain is 26.

So Bob's FAN is 95 (OB) +50 (Roll)-25 (DB) -15 (ArmourMod) +4 (Weapon Mod) = 109 The THT for chain is 26, so the final result is 83.

So Bob does (83/4.4) hits = 18.8 = 18 hits and a C critical (C threshold is 100 for "Ch" in the threshold table)

Easy, right?

Comparing this to Arms Law for Bobs attack value of 95+50-25 = 120 = 17 C Slash
Not a bad approximation for this highly scientific comparison!

The full table I'm not going to print as that's taking copyright too far, but you can pick up a copy of RMC I for about £15, it's also on drivethru RPG for \$15.

• I got the RMC I, but I didn't read it all. That seems exactly what I was looking for, thank you very much! – JoePerkins Oct 23 '16 at 12:11

Rolemaster was first published in 1980. For all you millennials out there, 1980 was near the end of the "dark ages" when computers were the size of cars and kept in specially air conditioned rooms and attended by a strange priesthood of computer scientists who performed elaborate rituals to keep them operating. There were desktop computers but these were still essentially toys still awaiting the "killer app" (which, by the way, was VisiCalc the first spreadsheet).

While you cannot prove a negative: it is more likely than not that these were generated by hand according to the algorithm in the designer's head.

That said, you could certainly derive a mathematical equation for the table. It is extremely unlikely that this equation will be simple. It will almost certainly look like the equations of a geocentric astronomer trying to deny the sun is at the centre of the solar system.

Build a lookup table - it will be easier.

• 1979 was the middle of the age of microcomputers (desk-sized; where “micro” was relative to mainframes) and we already had the first Apple Macintosh and the killer home app of the Basic programming language. So the history of computing is a bit off, but the general point stands: computers were rare and expensive and paper & pencil and eccentric designers is more likely. – SevenSidedDie Oct 19 '16 at 23:20
• The Rolemaster Combat Minion application has automated combat lookup tables: ironcrown.com/blog/2014/02/04/rolemaster-combat-minion-out-now. – RobertF Oct 20 '16 at 3:41
• I think they generated the data with some algorithm and then added some little manual changes, maybe. An reasonable approximation would be enough, though. Pretty interesting RobertF's link, I didn't remember they offer that software. – JoePerkins Oct 20 '16 at 16:25
• @SevenSidedDie The first Mac was released in 1984, but by 1979 you did have the Apple II (released in 1977) and early 1980 you had the Apple III, the VIC-20, and the ZX80 being released. – Vatine Oct 21 '16 at 10:47
• I first encounter Macs at the University of Sydney in 1986 and we that was the first year they had them. We used them in first year before moving to "traditional" Vax microcomputers. – Dale M Oct 21 '16 at 11:16

Looking for an xls version of the combat tables I found a revised version from The Guild Companion's issue of May 2002:

The goal was to find a solution for two well-known "armour anomalies", the relative ineffectiveness of lighter armour types and the "double penalty" (early concussion damage plus Quickness penalties) associated with heavier armour types.

For example, the new much reduced broadsword table would be:

The tables operate in much the same way as the regular weapon attack tables. The armour types are listed in columns and the results are derived from the standard OB - DB calculation. However, instead of giving an entry at each individual number up to 150, only intervals of when concussion damage and criticals occur are given. Each number listed within the tables along the critical severity type (A-E) rows indicates the minimum number needed to achieve that critical severity. Concussion damage is calculated by subtracting 75 from the final result of the OB – DB calculation and then dividing this result by the divisional factor 'Div'. The calculation of concussion damage can also be tabulated by referring to the Concussion Damage Calculation Table.

And an example of use:

Looking up the result of 112 on the revised Broadsword table against armour type 1 would yield the following.

Concussion Damage: (Result - 75) / 'Div'

[The division factor 'Div' can be found on the table for each AT]

(112 - 75) / '3' = 12.33 (round up to 13)

Critical Severity: 112 is more than 100 which gives a 'D' critical but less than 120 which gives an 'E' critical. The result of 112 falls within the 'D' critical range.

Critical Type: (Critical Type 1/Critical Type 2)

[Can be found along the same row as 'Crit' for each amour type]

In this case the critical types are S/P (slash/puncture). Odd numbers indicate the first critical type (slashes), while even numbers indicate the second (punctures). 112 is an even number, so a puncture is the critical type.

Final result: 13DP

It's not exactly what I was looking for, but it's a very good approximation :).

In a private project I did a re-editing and translation of RM 2nd Ed. to German, using LaTeX, giving me the "Director's Cut" RM rulebook I am using for my campaigns, with all the options decided upon, massaged into the main ruling text. (Yes, I am a bit mad that way. Mr. Charlton of I.C.E. told me as much in so many words when I told him of my work, asking him if there was a chance to get this greenlit for publishing. Sadly, the answer was no. ;-) )

This required me to transfer the Arms Law / Spell Law tables to LaTeX, a task I was not at all keen to do all manually. So I had a look at some way to "compress" the data in some way, and came up with a functional shorthand I could type with one hand on the numpad and one hand to mark my position in the table. (Using Perl scripts to turn the shorthand into readily-formatted LaTeX source at a later point.) Allow me to quickly explain the shorthand.

Each AT column gets "translated" into three lines of numbers:

1. Damage
2. Crit Severty (0: None, 1: A, 2: B, 3: C, 4: D, 5: E)
3. Crit Type (indexing a pre-defined array -- 1: Puncture, 2: Slash and so on)

Each line starts with the initial value (at 150), with following numbers indicating how many lines there were with that number / index. I used * <val1> <val2> <count> to indicate <count> groups of two alternating values (crit types), - <val1> <val2> <val3> <count> to indicate <count> groups of three alternating values (crit types), and / to indicate an end to decreasing / alternating numbers, the rest being verbatim values written out.

Taking the Shortsword table, for the AT 20 column, we get this:

5 25 24 24 24 9
3 3 4 9
3 13 / 1 3 2


For the Sling table, we get this at AT 20:

10 10 10 10 10 9 10 10 10 10 9
5 3 3 5 5 10
3 26


You see some further regularities in this which might be compressed even further (the four "10" / one "9" grouping for Sling damage), strongly hinting that the tables have been created based on some mathematic formula.

But having literally seen all the tables written down in this shorthand, I can also tell you that there are most likely several formulas at work here (so I did not bother trying to come up with an even more compressed shorthand than I already had). Note, for example, the "weird" tapering off of crit types in the Shortsword table, with puncture crits strewn in among the crush crits. Other tables do other kinds of "changing crits", or otherwise "break sequence" somewhere down the column.

I have never seen the formulas documented anywhere, even given the various "easier" combat resolution tables / systems provided by I.C.E. directly. None of those systems gives the exact results of the original AL / SL tables.

And that is after fixing some outright mistakes where it is obvious that 2nd edition Arms Law / Spell Law did not always list the numbers / criticals it was supposed to at some points (breaking otherwise obvious sequences). In that way, my Director's Cut may even be "more correct" than the original rules.

:-)

• The upside of having those shorthand files on disk being, I wrote another program that can now do all the table lookups for me. Unfortunately, I am pretty sure I may not distribute that either, as it is derived of the original Arms Law / Spell Law material... :-( – DevSolar Jan 8 at 15:16
• @animuson: This is ridiculous. I am being told by hostile moderators my contributions are not "up to par", and now you're engaging in a game of one-upmanship denying my wish to delete these unwelcome contibutions to which I hold copyright? I've brought this up with SE. You're harassing, just "because you can". You should be ashamed of yourself. – DevSolar Jul 11 at 9:00
• So, to be clear, you intend to keep trying deleting all of your material on this site (in defiance of site rules)? Am I correct in my understanding of what you are saying here? – Rubiksmoose Jul 12 at 15:24
• @Rubiksmoose I was informed, repeatedly, that my contributions are not up to par. So I would like to do you and myself a favor, remove the root cause, and have this ludicrous power play END. – DevSolar Jul 12 at 15:35
• @Rubiksmoose At this point I feel harassed and bullied by a bunch of people who enjoy ruining another person's community experience simply because they can. There is no empathy to be had, no constructive communication, no compromise. It's your way or no way. You arbitrarily delete one answer of mine, and undelete others I deleted. You are not acting as a moderator here, but as schoolyard bully. – DevSolar Jul 12 at 15:45