A Sanity Mechanic for D&D Type Gaming

The other day I looked at the role of the Sanity system in Call of Cthulhu, and how it creates another mechanical stress on the players and one that helps enforce the horror genre.  How would it work in something like D&D?

First - let's be clear on the goal.  In a horror-soaked D&D game, monsters are rare and otherworldly.  The experience of the supernatural is not commonplace - they represent a disturbance to the status quo and a violation of the natural order (from a human perspective).  A system that attempts to model the mental effects of horror implies that even hardened soldiers could be unnerved by direct exposure to the supernatural that defy categorization or understanding.  A mechanic would be put in place to attack the characters from an alternate angle and put pressure on the players as they face down supernatural threats.

In general, I prefer "less is more" and don’t like adding sub-systems so  I'd like Sanity mechanics to be simple, familiar, or both.

My first thought is something like this:  all characters have a permanent starting Sanity value equal to their Wisdom; from that point on, Sanity and Wisdom are not correlated.  Temporary Sanity goes up and down over the course of an adventure, but permanent Sanity rarely decreases and represents a hard cap.  There are some ways to heal temporary Sanity during an adventure, and lost temporary Sanity usually recovers completely between adventures.

Whenever a character is subjected to a horror, there's a chance their temporary Sanity decreases; the DM rolls a d20 against the characters current Sanity score (like an armor class), and if the roll meets or exceeds the score, the character loses some temporary Sanity.  (Conversely, if players prefer to roll, they're always trying to get under their temporary Sanity and 'miss' their Sanity).

Here's are some sample Sanity losses.  The amount is rolled randomly similar to weapon damage:

• Seeing a monster at a distance, witnessing a mundane killing or a fresh corpse - 1-2 points.
• Seeing a monster up close, finding a grisly murder scene, or experiencing unnatural omens or haunting effects - 1-4 points.
• Attacked by a supernatural threat or seeing hundreds of corpses - 1-6 points.
• Attacked by an overwhelming threat, like a horde of monsters or a giant thing; seeing the corpse of a loved one or friend; witnessing a supernatural killing - 1-8 points.
• Seeing a good friend gruesomely killed by a monster - 1-10 points

Cumulative losses within a single encounter caps at the maximum for the worst loss.  If the characters are attacked by a supernatural threat (loss 1-6) and one of the party members is gruesomely killed (1-10 loss), the maximum loss for both events is 10.

Furthermore, extremely weird and otherworldly monsters would have a kicker - seeing something like Great Cthulhu might add 1-6 points of loss to the roll (seeing Great Cthulhu  rise out of the harbor and scoop up a handful of sailors and toss them back like popcorn would cause potential 1-8 and 1-6 points altogether).  Really outré monsters like the Outer Gods or Great Old Ones may always strip a point of permanent sanity.  I haven't decided if there should be a minimum loss associated with certain encounters, even if the Sanity misses.  Since we’re treating it more like Sanity attacks and damage, it might be good to stay away from "auto damage".

SANITY EFFECTS
Once a character gets to zero temporary Sanity, they receive a -2 to all of their rolls and saving throws.  Once a character gets below -5 temporary Sanity, they're in deep shock and lose a point of permanent Sanity - an are they unable to function?  Do they gain a phobia or mental derangement?  I don't know yet - I need to see how other games have handled similar things and then run the ideas through some paces at a home game  (For now I'd treat "deep shock" as a Fear effect).  I'd also suggest a saving throw versus Death to avoid the loss of permanent Sanity.  At some point I'd expect a character might go permanently mad (at permanent Sanity = 0).

Anytime an NPC retainer or henchman loses half or more of their current Sanity, they need to make a morale or loyalty check.

Example:
Xameck the Mage and his small crew of mercenaries (Bart the Fighter, the priest Montjoy, and a retainer, Squire Deegan) are hired by the Burgomeister to discover the source of the grave robberies in the lonely cemetery beyond the village.  Climbing atop the Sarkhov Mausoleum, the group huddles down for an overnight vigil.  A village goodwife, recently deceased, was interred earlier in the day, and the lookout is spying on her fresh grave across the moonlit ghostyard.

A shambling, lurching figure emerges from the mists down below, startling Squire Deegan (make a check due to Seeing a Monster at a Distance).  Raising the alarm, the characters get to their feet and prepare missiles, but the monster lurches off into the darkness, tearing up clumps of earth with its hooves.  Since these guys are adventurers, they quickly climb down and begin to follow the monster's tracks.

The monster's path leads to an opened mausoleum, and the characters take a moment to light torches before entering the black interior.  There's only a large sarcophagus with a skewed slab for a lid within the decorative chamber.  Fearing an unholy terror, Montjoy waits at the end of the sarcophagus with a vial of holy water, while the two fighters get on either end of the slab and slide it open.

With a speed belying its ungainly size, the monster springs out of the depression and slashes Montjoy down the front of his chest with iron-hard claws.  As a 1st level cleric, Montjoy doesn't have too many hit points, and the other characters watch him drop to his knees, gurgling on his own blood before he dies.  While everyone in the group makes Sanity checks and prepares to draw weapons, the monster (in this case, a Lovecraft-style ghoul) barrels down a set of narrow stairs beneath the sarcophagus, and into a subterranean realm.

At this point, the characters have been threatened by a 1-2 Sanity loss (seeing the monster), a 1-6 point loss (attacked by the monster) and a potential 1-10 loss (seeing a friend killed right in front of them by the monster).  The cumulative maximum is still 10 points because these would all count as a single encounter.  It's possible some characters with low Sanity scores are "shaken", taking a -2 to rolls, and Squire Deegan might need a morale check before being willing to enter the ghoul's realm.

Obviously, we need to try the rules on and refine the approach, but just reflecting on the sample encounter, I can see that adding any kind of Sanity mechanic changes the complexion of even a "mundane" supernatural encounter into something different and makes each encounter more impactful.  I didn't spend much time with the Ravenloft 2E rules back in the day, and I've been thinking of checking those out as well to see what the mothership was doing to support horror-flavored D&D back in the 90's.  Anyone familar with the 2E Ravenloft setting?  (Someone pointed out Crypts & Things has a Sanity mechanic too - I'll have to check it out and see how it's implemented).

RECOVERING SANITY
In the interests of carousing rules and soaking loose cash, the primary way to recover lost Sanity is to spend some money in between adventures - each day of spending 100gp (per character level) recovers 1-6 temporary Sanity points.  This money could be spent on any appropriate activity stipulated by the player as something relaxing or important to the character, but it can't provide other material benefits.  Examples include carousing, tithing to the church, research, or training.

Once per day while adventuring, the party leader can give a rousing speech to each character.  If the leader succeeds on a reaction roll (rolling a 9-12 on a roll of 2d6, modified by Charisma) the characters are inspired and gain 1-6 Sanity back.  Consider it a once-per-night pep talk or morale boost.

I'd have to go back through the clerical magic system and identify appropriate spells that should interact with Sanity hit points and damage; spells like Fear may cause Sanity damage in addition to their other effects, whereas Remove Fear could recover Sanity damage similar to a Cure Light Wounds.  Maybe high level spells like Restoration can restore permanent Sanity points.