Forbidden Knowledge

FORBIDDEN KNOWLEDGE LEVEL 20 HD REQUIRED FOR SKILL!
==What Is Sanity?==
Sanity is the natural mental state of ordinary life. Normal mental balance is endangered when characters confront horrors, entities, or activities that are shocking, unnatural, and bewildering. Such encounters cause a character to lose points from his Sanity score, which in turn risks temporary, indefinite, or permanent insanity. Mental stability and lost Sanity points can be restored, up to a point, but psychological scars may remain.
Insanity occurs if too many Sanity points are lost in too short a time. Insanity does not necessarily occur if Sanity points are low, but a lower Sanity score makes some forms of insanity more likely to occur after a character experiences an emotional shock. The character’s Sanity may be regained after a few minutes, recovered after a few months, or lost forever.
A character may regain Sanity points, and even increase her Sanity point maximum. However, increasing a character’s ranks in the Knowledge (forbidden lore) skill always lowers her maximum Sanity by an equal amount.
==Forbidden Knowledge==
The Sanity rules assume that some knowledge is so alien to human understanding that simply learning of its existence can shatter the psyche. While magic and nonhuman races form an everyday part of a d20 character’s life, even a seasoned adventurer cannot conquer or understand some things. Knowledge of these secrets and creatures is represented by a new skill that goes hand in hand with a character’s Sanity score: Knowledge (forbidden lore).
This type of knowledge permanently erodes a character’s ability to maintain a stable and sane outlook, and a character’s current Sanity can never be higher than 99 minus the modifier the character has in the Knowledge (forbidden lore) skill. This number (99 minus Knowledge [forbidden lore] ranks) is the character’s maximum Sanity.
====Knowledge (Forbidden Lore) (None)====
You know That Which Should Not Be Known. You have had horrible supernatural experiences and read forbidden tomes, learning truly dark secrets that have challenged everything you thought you knew. Since these revelations defy logic or commonly accepted fact, it does not matter how intelligent or wise you are when using this skill—only how much exposure to these dark secrets themselves you have experienced.
=====Check=====
Answering a question about the horrible deities and secrets that lurk at the edges of reality has a DC of 10 (for really easy questions), 15 (for elementary questions), or 20 to 30 (for difficult or really tough questions). Unlike in other fields of study, there are almost no really easy questions associated with this dark knowledge.
You can use this skill to identify monsters and their special powers or vulnerabilities. In general, the DC of such a check equals 10 + the monster’s HD. A successful check allows you to remember a bit of useful information about that monster. For every 5 points by which your check result exceeds the DC, the GM can give another piece of useful information.
The GM can decide which monsters are subject to the Knowledge (forbidden lore) skill and which monsters are subject to one of the standard Knowledge skills. For example, the GM may rule that Knowledge (the planes) is still the relevant skill for learning or knowing about outsiders, rather than allowing them to be iedntified by Knowledge (forbidden lore). However, in most campaigns that use the Sanity variant, aberrations and oozes should be able to be identified by Knowledge (forbidden lore) rather than by Knowledge (arcana) and Knowledge (dungeoneering) respectively.
=====Action=====
Usually none. In most cases, making a Knowledge check doesn’t take an action—you simply know the answer or you don’t.
=====Try Again=====
No. The check represents what you know, and thinking about a topic a second time doesn’t let you know something that you never learned in the first place.
=====Special=====
You cannot gain ranks in this skill by spending skill points. You can only gain ranks by reading forbidden tomes or having experiences with horrible creatures. Each rank you gain in this skill permanently reduces your maximum Sanity by 1 point: The more you know about the horrible truths underlying reality, the less capable you are of leading a normal life.
A character’s first episode of insanity (that is, an occurrence of temporary or indefinite insanity) bestows 2 ranks in the Knowledge (forbidden lore) skill, thereby lowering his maximum Sanity by 2 points. Each time a character fails a Sanity check and endures another episode of insanity, he gains an additional rank in Knowledge (forbidden lore).
For example, Caldark has 1 rank of Knowledge (forbidden lore) after reading a strange manuscript. She then steps outside, sees a chaos beast, and goes indefinitely insane, her raving mind failing to understand the strange creature she has encountered. Since she has never gone insane before, her player adds 2 ranks of Knowledge (forbidden lore) to Caldark’s character sheet. Now Caldark’s Maximum Sanity is 96 (99 minus 3 ranks of Knowledge [forbidden lore]).
You cannot take the Knowledge (forbidden lore) skill during character creation. However, the skill has no maximum rank; your level does not limit the number of ranks in Knowledge (forbidden lore) that you can acquire.
==Sanity Points==
Sanity points measure the stability of a character’s mind. This attribute provides a way to define the sanity inherent in a character, the most stability a character can ever have, and the current level of sane rationality that a character preserves, even after numerous shocks and horrid revelations.
Sanity is measured in three ways: starting Sanity, current Sanity, and maximum Sanity. Starting and current Sanity cannot exceed maximum Sanity.
====Starting Sanity====
A character’s starting Sanity equals his Wisdom score multiplied by 5. This score represents a starting character’s current Sanity, as well as the upper limit of Sanity that can be restored by the Heal skill (see The Heal Skill and Mental Treatment, later in this section). After creation, a character’s current Sanity often fluctuates considerably and might never again match starting Sanity. A change in a character’s Wisdom score changes his starting Sanity in terms of what treatment with the Heal skill can restore. Current Sanity, however, does not change if Wisdom rises or falls.
====Current Sanity====
A character’s current Sanity score fluctuates almost as often as (and sometimes much more often than) his hit points.
=====Making a Sanity Check=====
When a character encounters a gruesome, unnatural, or supernatural situation, the GM may require the player to make a Sanity check using percentile dice (d%). The check succeeds if the result is equal to or less than the character’s current Sanity.
On a successful check, the character either loses no Sanity points or loses only a minimal amount. Potential Sanity loss is usually shown as two numbers or die rolls separated by a slash, such as 0/1d4. The number before the slash indicates the number of Sanity points lost if the Sanity check succeeds (in this case, none); the number after the slash indicates the number of Sanity points lost if the Sanity check fails (in this case, between 1 and 4 points).
A character’s current Sanity is also at risk when the character reads certain books, learns certain types of spells, and attempts to cast them. These Sanity losses are usually automatic (no Sanity check is allowed); the character who chooses to undertake the activity forfeits the indicated number of Sanity points.
In most cases, a new Sanity-shaking confrontation requires a new Sanity check. However, the GM always gets to decide when characters make Sanity checks. Confronting several horribly mangled corpses at one time or in rapid succession may call for just one Sanity check, while the same corpses encountered singly over the course of several game hours may require separate checks.
=====Going Insane=====
Losing more than a few Sanity points may cause a character to go insane, as described below. If a character’s Sanity score drops to 0 or lower, she begins the quick slide into permanent insanity. Each round, the character loses another point of Sanity. Once a character’s Sanity score reaches -10, she is hopelessly, incurably insane. The Heal skill can be used to stabilize a character on the threshold of permanent insanity; see The Heal Skill and Mental Treatment, below, for details.
A GM’s description of a Sanity-shaking situation should always justify the threat to a character’s well-being. Thus, a horde of frothing rats is horrifying, while a single ordinary rat usually is not (unless the character has an appropriate phobia, of course).
====Maximum Sanity====
Ranks in the Knowledge (forbidden lore) skill simulate a character’s comprehension of aspects of the dark creatures at the edges of reality. Once gained, this horrible knowledge is never forgotten, and the character consequently surrenders mental equilibrium. A character’s Sanity weakens as his comprehension of these hidden truths increases. Such is the way of the universe.
A character’s current Sanity can never be higher than 99 minus the character’s ranks in the Knowledge (forbidden lore) skill. This number (99 minus Knowledge [forbidden lore] ranks) is the character’s maximum Sanity.
==Loss Of Sanity==
Characters ordinarily lose Sanity in a few types of circumstances: when encountering something unimaginable, when suffering a severe shock, after casting a spell or when learning a new spell, when being affected by a certain type of magic or a particular spell, or when reading a forbidden tome.
====Sanity Resistance====
The Sanity mechanic was originally created to mimic the effect that the unspeakable horrors of the Cthulhu Mythos would have on normal folk from a world much like our own. Since d20 characters live in a world of magic and monsters, however, the GM might want to make them less susceptible to Sanity loss caused by encountering strange creatures (see Table: Sanity Loss from Creatures) by allowing them to have a measure of Sanity resistance, which is tied to one of two attributes.
Each character can be allowed to have Sanity resistance equal to his character level. Alternatively, each character can be allowed to have Sanity resistance equal to his Wisdom modifier. (Obviously, the second alternative will produce lower Sanity resistance figures in most cases.) This number is the amount of Sanity loss a character can ignore when he encounters a creature that requires a Sanity check.
The GM may decide that Sanity resistance also applies to certain kinds of severe shocks (although it might not apply to personally horrific experiences, such as seeing a close friend die) and to the casting or learning of spells.
====Encountering the Unimaginable====
When people perceive creatures and entities of unspeakable horror, this experience costs them some portion of their minds, since such creatures are intrinsically discomforting and repellent. We never lose awareness of their slimy, fetid, alien nature. This instinctive reaction is part and parcel of humans, elves, dwarves, and other humanoid races. In this category, we can include supernatural events or agents not always recognized as specifically devoted to these dark gods, such as hauntings, zombies, vampires, curses, and so on.
Table: Sanity Loss from Creatures provides some default Sanity loss values for encountering creatures, based on their type and size. These are only default values—the GM can and should adjust individual monsters he deems more or less horrible than others of their size. An aasimar, for instance, hardly presents a Sanity-shaking sight, and should probably be treated as a humanoid rather than an outsider. On the other hand, a vargouille—a Small outsider appearing much like a flying, bat-winged head—might provoke a much more visceral reaction than other Small outsiders.
In addition, certain types of monstrous behavior might force additional Sanity checks, much like those described under Severe Shocks, below. For instance, an aboleth is an unnerving sight, but watching one transform your best friend with it's slime should certainly force another check, with losses appropriate to the situation.
In most d20 games, no character should need to make a Sanity check when encountering an elf, dwarf, or other standard humanoid race, or for encountering domesticated or otherwise commonplace animals. In some cases, even humanoid races such as orcs and goblins might be so common as to not cause Sanity loss either.
=====Specific Monsters and Sanity=====
Some monsters have additional or variant special abilities when using the Sanity variant.
======Allip======
The allip’s madness ability causes the loss of 2d6 Sanity points rather than the normal effect.
======Derro======
The derro’s madness ability protects these creatures from any further Sanity loss. Sane derro (especially derro player characters) track Sanity points normally.
=====Monstrous Characters and Sanity=====
In most cases, the GM does not need to keep track of a monster’s Sanity score, but sometimes, especially when in the hands of a player, monsters need Sanity scores just as other characters do.
Although most campaigns that use the Sanity variant limit players to creating characters from the standard player character races, it’s still easy to envision a world where one or two monstrous races are so common or so integrated into the culture of other races that the GM wants to present them as viable player character options. In these cases, the monsters available as player character races should never provoke a Sanity loss from other characters or NPCs, and these creatures should have a Sanity score and track their Sanity losses just like characters made with the standard PC races. A monster should never lose Sanity for seeing others of its race (spectres don’t lose Sanity when encountering other spectres, and so on). In all cases, what causes Sanity loss for a specific creature is in the hands of the GM.