(note—those of you who have played the “Call of Cthulhu” roleplaying game will be familiar with the majority of these mechanics. However, they have been altered for use with the Ravenloft campaign setting. Please ask your DM for further information, if you have any questions.)
Each character in this world begins with a Sanity score equal to five times their Wisdom score (5xWis). This score will fluctuate as the game goes on, gaining and losing Sanity points, particularly if the Wisdom score is changed.
The absolute maximum sanity that a character can have is 99. Even the most stalwart characters have a slight chance of just “losing it”.
All characters will also be granted a “Sanity Buffer” equal to their Wisdom modifier. This represents a character’s resilience towards mind-shattering threats. The Sanity buffer will apply to such events like seeing horrific creatures and witnessing a gruesome ritual, however it will not apply to Sanity losses incurred by spells, magic items or Ravenloft tomes (to be described shortly).
Sanity is tested differently than most other abilities in D&D. Rather than using a d20, you must roll percentage dice. A roll EQUAL TO OR LESS than your current Sanity score incurs either no loss or a lesser loss, depending on the situation. A roll HIGHER than your current Sanity incurs the higher loss.
Example: Gareth the Barbarian sees a Mind Flayer eat someone's brain. Gareth's current Sanity is 74, and he has a Wisdom score of 14 (+2 modifier). Bob the DM looks up the Sanity loss in this event, and sees that it is 2/1d8. Gareth rolls percentile dice, getting a result of 84 (a failure). At this point Gareth would lose between 1 and 8 points of Sanity, reduced by 2 because of his Sanity buffer (from his high Wisdom). Had Gareth rolled a lower number, 33 perhaps, he would incur no loss because his Sanity buffer (2) is the same amount as the loss.
The skill "Knowledge: Ravenloft" will be replaced by “Ravenloft Mythos”. No character may choose ranks in this skill, but instead may gain them by experiencing features and theories on the Mists. However, each rank of Ravenoft Mythos reduces a character’s maximum sanity by 1. Similar to a Sanity check (detailed above), Ravenloft Mythos is tested by a percentage roll. A character must roll AT or BELOW their current ranks in Ravenloft Mythos to succeed on a check. All Clerics and Paladins of the Goddess Ezra automatically gain 5 free ranks in Ravenloft Mythos. Their maximum Sanity scores are reduced by 5, accordingly.
The skill “Heal” will also have applications for psychological healing and therapy. DCs for short and long-term care will be set by the DM, as will amounts of recovered Sanity points. Any character with 5 ranks in “Knowledge: Psychology” or “Hypnotism” will gain a +2 synergy modifier to any Heal checks involving psychiatric care. Sanity can also be regained through treatment in clinics…
Certain books and tomes scattered throughout the Land of the Mists hold dire secrets and spells which can be used by any character. However, these powers do not come without great risks to one’s sanity. Following the rules from the “Call of Cthulhu” game, these tomes incur Sanity loss upon both initial contact and upon completion. Typical powers from these tomes include (but are not limited to): ranks in Ravenloft Mythos, a new special ability, arcane spells, spell-like abilities and ability points.
Arcane spellcasters (Bards, Wizards and Sorcerers), due to the nature of their incantations, are at great risk for losing Sanity. In one twenty-four hour period, a caster may only cast three plus their caster level in spells (3+caster level/24hours) without risk of Sanity loss. Every spell beyond that limit incurs a Sanity check of 0/1 (That is, 0 points lost on a successful roll and 1 point lost on a failure). The Sanity buffer does not apply to this loss. If a spellcaster would receive a temporary or indefinite insanity from casting a spell, the caster must make a Concentration check (DC 25) and a Spellcraft check (DC 10+spell level) to successfully cast the spell.
Every character, upon gaining a new level, receives 1d6 Sanity points. No re-rolls will be granted.
Temporary insanities set in if a character loses 7 Sanity points in a 48 hour period. These are usually easily cured and will likely just “go away” in a few minutes. Indefinite insanity sets in if a character loses ¼ of their starting sanity. These are not easily cured, and will require some distinct role-playing on your part to portray. In both cases, your DM will take you aside and alert you as to what has happened.