Ability score
From NWNWiki
An ability score is the numeric rating of one of the six abilities. Humans establish the scale for these ratings, with a "typical" human having a score of 10 in each ability (and with a score of 0 corresponding to no ability). In most cases, the ability score is "primary" in that it is what gets modified through various means, but it is the derived ability modifier that actually affects what happens in the game.
The game engine allows an ability score to range from 3 to 255. However, player characters are incapable of reaching this maximum through normal means, as starting ability scores are limited to 20, and the ability cap limits magical enhancements to +12. The highest ability score achievable by a player character through normal means is 57 (strength). The highest score achievable without bonuses from feats and race is 40.
[edit] Increasing scores
Player characters are assigned ability scores from 8 to 18, before applying any racial modifiers, at character creation through a point buy system. In addition, every four character levels a single ability score can be increased by one. Furthermore, certain feats (dragon abilities of red dragon disciples and the "great ability" epic feats) can increase base scores.
Items, spells, etc. ("magical means") can further affect ability scores, subject to the +12 ability cap. When a score is increased by magical means, it is shown in green on the character sheet; when is it decreased, it is shown in red. When a score is not modified (or has a net modifier of +0) by magical means, it is shown in white. It is this unmodified score (the base score) that matters when meeting the prerequisite of a feat.
[edit] Spellcasting
Ability scores affect the highest level spell that can be cast or known by a spellcaster. The ability that is the casting ability depends upon class: intelligence for wizards; wisdom for clerics, druids, paladins, and rangers; and charisma for sorcerers and bards.
In order to learn a spell of a given level, the caster must have a base casting ability score of at least 10 + spell level. In order to prepare or cast a known spell, the caster must have a modified casting ability score of at least this same number; having the casting ability reduced will cause the loss of all spell slots that are too high a level for the reduced ability.
