Using Unknown Armies madness rules in Call of Cthulhu (archive)
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Version 3
Contributed by David Farnell, January 2000

UNKNOWN ARMIES is TM and (C) Greg Stolze and John Tynes, and is used here with permission.

The previous two versions involved essentially minor rule-changes to the CoC Sanity rules; this one goes much further, simply transplanting the Madness rules from UA and modifying them to fit the Basic Role-Playing structure. Using these rules will require access to the _Unknown Armies_ Rulebook, by Greg Stolze and John Tynes (Atlas Games #AG6000, ISBN 1-887801-70-7).

Now, read the chapter in UA on Madness. Get comfortable with it. Ready? OK.

As you can see, if we want to use these rules in CoC, the replacement of the Sanity rules is relatively simple, but since Sanity is such a big part of CoC (monsters, tomes, spells, actions, etc.), we still need to do a lot of tinkering to make it work smoothly. Also, the concept of the Mythos is, at times, somewhat different, somewhat harsher than the concept of the Unnatural in UA.

First, the SAN roll. Keep it the same as CoC: POWx5. Unlike CoC, it is not reduced by losing Sanity points—it stays the same no matter how crazy the character gets. However, in keeping with the idea that knowledge of the Mythos is corrosive to the human mind, SAN = (POWx5) minus Cthulhu Mythos skill.

[Example: Prof. Joseph Camp has a POW of 17. His basic SAN roll is 85%. However, he has acquired Cthulhu Mythos 38%, which reduces his SAN roll to 47%. Luckily (or not), he has encountered so much horror in his long life that he rarely has to make a roll due to his Hardening.]

Rolling against Madness is otherwise pretty much like UA—when you have a stress event, you roll versus SAN. If you fail, you take a check in the appropriate Failed box. If you succeed, you take a check in the appropriate Hardened box. Such stress events are ranked from 1-10 as "Stress Ratings." Follow the UA rules for Hardening and going insane.

Now, most Mythos encounters will fit into the five categories, usually "The Unnatural," but some are particularly mind-shattering, and go beyond the UA rules. For example, in the UA rules, one can only check one Failed box per event, which limits the amount of damage. This doesn't really seem sufficient for someone who encounters Great Cthulhu itself, or reads a particularly good translation of the Necronomicon.

Exceptional Mythos Stress: If the Keeper determines the situation is monstrously alien enough, then the Stress Rating can be above 10. This has two effects.

First, Hardening is obviously useless, since it maxes out at 10. Nobody can be Hardened enough to shrug off the worst of the Mythos.

Second, for every Rank above 10, the player has to roll once. This means one stress event can entail multiple rolls, resulting in the possibility of checking more than one Failed and/or Hardened box. With an Rank 15 encounter, it is quite possible for a perfectly sane character to go Permanently Mad within a single round.

[Example: Agent OAKTREE is present for a summoning of Shub-Niggurath. Let's rank that as The Unnatural 15. OAKTREE has a SAN roll of 63%. He has to roll 5 times, and makes 2 successes and 3 failures. In a single round, he has gained Hardened 2 and Failed 3 in his Unnatural row.]

To handle the "short-term freak-out" effect, if you suffer more than one Failure in a single round, just make the freak-out more severe, or combine effects. In the above example, OAKTREE might Frenzy and Panic simultaneously, running and attacking anything in his path, including friends and innocent bystanders. Extreme Frenzy might include dismemberment and cannibalism (of an enemy, a friend, or even oneself), which in the aftermath might require testing against Violence and Self.

Ranking Mythos Stresses: A simple rule of thumb in converting CoC SAN loss (for seeing monsters, reading tomes, casting spells) to UA Stress Ranks is "Max SAN loss = Stress Rank."

[Example: A Ghoul has SAN loss 1d6. The Stress Rank is therefore 6.]

That may sound a bit high, but consider that under this system, meeting a Ghoul is actually less stressful than "See[ing] an animal with human features" (Unnatural Stress Rank 8). However, it definitely is too high in some cases, such as reading the better translations of the Necronomicon (Stress Rank 20!) or meeting Shub-Niggurath (Stress Rank 100!!). Taking these literally would simply require too much dice rolling, and the players wouldn't have a chance. Here's a recommendation for Stress Ranks above 10:

Max SAN loss 11-12 = Stress Rank 11

Max SAN loss 13-16 = Stress Rank 12

Max SAN loss 17-20 = Stress Rank 13

Max SAN loss 21-50 = Stress Rank 14

Max SAN loss 51-100 = Stress Rank 15

Sanity and Spells: When spells require a loss of Sanity in CoC, convert by figuring the amount of Sanity that would have been lost, and use it as a Stress Rank as above.

Horrific Insight: Every time a character Fails a Stress Test in an encounter with the Mythos, he gains one point of Cthulhu Mythos skill. Note that this does not have to be only in the Unnatural category. Going mad while being tortured by a Byakhee is good for some Mythos insight, and suffering checks against Isolation while wandering lost in Carcosa should count, too. And remember that every point of Cthulhu Mythos skill gained causes an equal penalty to the SAN roll.

Regaining Sanity: Beyond the therapy options in UA, players in CoC can regain lost SAN in a variety of ways—defeating monsters, gaining 90% in a skill, saving innocents, etc. A simple way to convert this is to reward players with the chance to erase Failed and/or Hardened checks at the end of a scenario. However, the Keeper should practice great restraint, doling out these erasures only for important successes, and making them category-appropriate. Sanity should be much harder to recover than it is to lose. And the ever-lowering SAN Roll should only increase if Cthulhu Mythos knowledge is somehow forgotten (perhaps through a botched trepanation, with an accompanying loss of INT). This is CoC, after all.

Please visit the Unknown Armies website.

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