Every player character has six character ability scores:
Strength governs modifiers in melee combat, opening/lifting things, and carrying capacity.
Intelligence governs ability to learn languages and magic-user/illusionist spells.
Wisdom governs ability to resist certain mental attacks and clerical/druidical spell casting ability.
Dexterity governs modifiers in missile weapon combat and the ability to react in combat; governs modifiers to Armor Class based on agility/quickness and likewise, saving throws against damaging effects or those affected by balance/agility.
Constitution governs modifiers to Hit Points and the ability to survive system trauma such as magical aging or being raised from the dead/resurrected)
Charisma governs modifiers to Encounter Reaction with other creatures and NPC Loyalty; Also sets the limit on the number of henchmen available to the character)
These scores are generated when the character is created and rarely change. They indicate what tasks the character is suited to accomplish although it is up to the character to decide their Character Class.
All scores are generated on a scale of 3 to 18, although, in special cases, adjustments can exceed this range or restrict it. Exceptional Strength for fighters/rangers/paladins is rolled separately should the character achieve an 18 in Strength.
Legendary Ability Scores. In some cases, certain special characters or creatures will possess a Legendary Ability Score. This means the score falls outside of the range of 3 to 18. Statistics are given for these (rare) circumstances.
While rare, this can be done by using special magic items or wish-type magic (See Spells, wish). If using a wish to increase an ability score, once any score reaches 18 or above, each wish will raise the score only by 1/10th of a point. This means it would take 10 wishes to increase a score of 18 to 19. Exceptional Strength may be raised in a similar manner (adding 10% per wish). Some magic (at least avatar-level) can bypass this limitation.
Certain magic, including curses, can lower ability scores temporarily or permanently. If permanent, magic must be used to restore the score and this is usually noted in the description of the effect. Some creatures have the ability to lower scores through special attacks. (cf. Lamia or Shadow) If not otherwise indicated, ability score "drain" is permanent and ability score "damage" is temporary. Age can also lower ability scores. If not otherwise indicated, permanent loss of ability score points can be restored with wish-type magic or a restoration spell. Ability score points lost due to aging cannot be restored except through subsequent age related modification.
Effects of the lowered score against prerequisites depend on the type of prerequisite:
Race. After character creation, loss of ability scores have no effect on race, although racial abilities may be altered by the new score.
Class. After character creation, loss of ability scores will not impact the character’s ability to operate in an existing character class or the ability to gain levels in the existing class. Class abilities are only affected if tied directly to an ability score, such as spell casting.
Spell Casting. Mages require a minimum Intelligence of 9 and for Priests, a minimum Wisdom of 9. If the required ability score drops under 9, all spell casting ability is lost until it is raised above 9.
Hit Points. If a character’s Constitution score is decreased, even temporarily, the character will suffer the loss of any hit points due to Constitution adjustment per hit die immediately. Likewise, when the score is raised, even temporarily, hit points are gained immediately for every hit die. A character that is killed due to loss of Constitution modifier will actually slip into a coma for 10 rounds before actually dying.