The math behind the SIEGE system

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rabindranath72
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The math behind the SIEGE system

Post by rabindranath72 » Thu Mar 08, 2012 10:21 am

I have recently worked out a bit of the math behind D&D3e and how it relates to C&C, which uses a similar system of relative difficulties. It should be noted that 3e saves in particular scale really well with level, to the contrary of the C&C ones where even a difference of three levels can prove fatal due to non-Prime attributes.
Note that despite the system of relative difficulties, the 3e system retains most of the basic assumptions of (A)D&D, since only rarely saves become impossible. For a game like C&C which aims to evoke the "feel" of the old editions, the scaling of saves is a sore point.

There are actually two degrees of freedom in this problem. The first one pertains to the basic success (as defined by the CB, and evaluated on a level-by-level basis, keeping all other factors equal.) The second one pertains to how these basic successes vary when the levels of the opposition changes.

All things being equal, a 3e character has fixed DC (or CB in C&C terms) of 8 for the favorable save category, and a varying DC for the unfavorable category(ies) which ranges from 10 at 1st level, to 14 at 20th level (with a mean of 11.85 and a median of 12); note this implies that saves get slightly worse as level increases, which might seem weird, though the game assumes that high level characters have magical ways to improve their saves, which balances things out again. In C&C terms, the favorable (unfavorable) categories would roughly map to the Primary and Secondary attributes.

So, if one wanted to retain the good (and reasonable) basic chances of D&D3e and apply them to C&C, the new CBs should be set to 8 for Primary attributes, and 12 for Secondary attributes. For scaling, one should set the CL at 1/2 level per 3e.

Going with full level means that there cannot be a level difference larger than 8 for a save to succeed, all other factors being equal (but see the comment at the start about impossible saves.)

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Boddynock
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Re: The math behind the SIEGE system

Post by Boddynock » Fri Mar 09, 2012 1:29 am

This is an interesting point, I'd like to throw out an example. Just to make sure I'm reading this right.

In a game where I'm a wizard with a non-prime Con, my character would have a CB of 12, and when the party is attacked from behind by an giant centipede, and the fighter forgot to have my back due to distraction. That 4th level poison of the centipede only adds 2 to the CB, making a CC of 14 for my Con check?

Would that be a fair example of your proposed system?
Last edited by Boddynock on Fri Mar 09, 2012 3:08 pm, edited 1 time in total.
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rabindranath72
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Re: The math behind the SIEGE system

Post by rabindranath72 » Fri Mar 09, 2012 10:20 am

Boddynock wrote:This is an interesting point, I'd like to throw out an example. Just to make sure I'm reading this right.

In a game where I'm a wizard with a non-prime Con, my character would have a CB of 12, and when the party is attacked from behind by an giant centipede, and the fighter forgot to have my back due to distraction. That 4th level poison of the centipede only adds 2 to the CB, making a CL of 14 for my Con check?

Would that be a fair example of your proposed system?
Yes, non-prime Con CB would be 12 (or 8 if you were a Barbarian, say.)
Then you can choose to either go full level per standard C&C rules (so the CC=12+4=16) or the "d20-like" rules of half-level (so the CC=12+4/2=14.)
Then when rolling d20 for the check, you would either add your class level, or half your class level.

Note you write "CL of 14" but that is the wrong word; the CL is the term you add to the CB. The total is the Challenge Class=CB+CL.
Last edited by rabindranath72 on Fri Mar 09, 2012 10:27 am, edited 1 time in total.

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Re: The math behind the SIEGE system

Post by rabindranath72 » Fri Mar 09, 2012 10:26 am

If you read the SIEGE chapter in the CKG, you can see that originally the primes system was based on CB of 10 for primary attributes, 12 for secondary etc. (they also had tertiary etc. up to the 6th ability score.) For some weird reason (which they don't explain) they went with the current scaling, which IMO makes things far more difficult than they need to be, considering that the aim of the game is to reproduce the dynamics of old-school (A)D&D. Apparently they didn't take into account scaling, and the fact that the saves system in (A)D&D was absolute, not relative. The 3e designers instead went with a relative system, which still retains the range of success of the absolute system; very sleek and elegant design.
As a result, a scenario converted from AD&D might retain the same dynamics in 3e (in terms of expected lethality, success etc.,) but not in C&C.

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Re: The math behind the SIEGE system

Post by Boddynock » Fri Mar 09, 2012 3:28 pm

I only briefly read the Siege part on the CKG, but I didn't really think ahead on high reaching games, it does feel that the makers of C&C really expect games to be low level, or at least the first 12 with a couple of nods of games beyond that. Anyway I made the change to my post, and I actually co-opted your system to my own C&C notes. Now I got some changes to make to character sheets.
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Re: The math behind the SIEGE system

Post by rabindranath72 » Fri Mar 09, 2012 4:39 pm

Boddynock wrote:I only briefly read the Siege part on the CKG, but I didn't really think ahead on high reaching games, it does feel that the makers of C&C really expect games to be low level, or at least the first 12 with a couple of nods of games beyond that. Anyway I made the change to my post, and I actually co-opted your system to my own C&C notes. Now I got some changes to make to character sheets.
That's the problem; it's not a matter of high level vs. low level, it's a problem that regardless of character levels, characters are not able to face an opposition even slightly more powerful than themselves (four levels more are enough for a save to be impossible unless the character has attribute modifiers or some magic item.)
For example, even a 10th level character is practically toast if he faces a dragon and he doesn't have a prime in, say, Dexterity, since dragons have lots of hit dice.
Compare this with the chances of a 2e character vs. a dragon, and you will see that even if the challenge is roughly the same, the 2e character will have a much better chance to survive. This IMO is a serious bug in the game, since it does not emulate the dynamics of (A)D&D at all as they say it does.

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Re: The math behind the SIEGE system

Post by Boddynock » Fri Mar 09, 2012 6:22 pm

Good point, I actually adapted your system, right now with full HD/Levels. See where it goes and make changes when necessary. Thanks for the suggestion
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