Whenever you attempt an action that has some chance of failure, you roll a twenty-sided die (d20). To determine if your character succeeds at a task you do this:
If the result equals or exceeds the target number, your character succeeds. If the result is lower than the target number, you fail.
Note: The target number is known as a Difficulty Class (DC).
Dice rolls are described with expressions such as “3d4+3”, which means “roll three four-sided dice and add 3” (resulting in a number between 6 and 15). The first number tells you how many dice to roll (adding the results together). The number immediately after the “d” tells you the type of die to use. Any number after that indicates a quantity that is added or subtracted from the result.
d%: Percentile dice work a little differently. You generate a number between 1 and 100 by rolling two different ten-sided dice. One (designated before you roll) is the tens digit. The other is the ones digit. Two 0s represent 100.
A modifier is any bonus or penalty applying to a die roll. A positive modifier is a bonus, and a negative modifier is a penalty.
In most cases, modifiers to a given check or roll stack (combine for a cumulative effect) if they come from different sources and have different types (or no type at all), but do not stack if they have the same type or come from the same source (such as the same spell cast twice in succession). If the modifiers to a particular roll do not stack, only the best bonus and worst penalty applies. Dodge bonuses and circumstance bonuses however, do stack with one another unless otherwise specified.
The bonus or penalty associated with a particular ability score. Ability modifiers apply to die rolls for character actions involving the corresponding abilities.
An alchemical bonus is granted by the use of a non-magical, alchemical substance such as antitoxin.
An armour bonus applies to Armour Class and is granted by armour or by a spell or magical effect that mimics armour. Armour bonuses stack with all other bonuses to Armour Class (even with natural armour bonuses) except other armour bonuses. An armour bonus doesn’t apply against touch attacks, except for armour bonuses granted by force effects (such as the mage armour spell) which apply against incorporeal touch attacks, such as that of a shadow.
A circumstance bonus (or penalty) arises from specific conditional factors impacting the success of the task at hand. Circumstance bonuses stack with all other bonuses, including other circumstance bonuses, unless they arise from essentially the same source.
A competence bonus (or penalty) affects a character’s performance of a particular task, as in the case of the bardic ability to inspire competence. Such a bonus may apply on attack rolls, saving throws, skill checks, caster level checks or any other checks to which a bonus relating to level or skill ranks would normally apply. It does not apply on ability checks, damage rolls, initiative checks or other rolls that aren’t related to a character’s level or skill ranks. Multiple competence bonuses don’t stack; only the highest bonus applies.
A deflection bonus affects Armour Class and is granted by a spell or magic effect that makes attacks veer off harmlessly. Deflection bonuses stack with all other bonuses to AC except other deflection bonuses. A deflection bonus applies against touch attacks.
A dodge bonus improves Armour Class (and sometimes Reflex saves) resulting from physical skill at avoiding blows and other ill effects. Dodge bonuses are never granted by spells or magic items. Any situation or effect (except wearing armour) that negates a character’s Dexterity bonus also negates any dodge bonuses the character may have. Dodge bonuses stack with all other bonuses to AC, even other dodge bonuses. Dodge bonuses apply against touch attacks.
An enhancement bonus represents an increase in the sturdiness and/or effectiveness of armour or natural armour, or the effectiveness of a weapon, or a general bonus to an ability score. Multiple enhancement bonuses on the same object (in the case of armour and weapons), creature (in the case of natural armour), or ability score do not stack. Only the highest enhancement bonus applies. Since enhancement bonuses to armour or natural armour effectively increase the armour or natural armour’s bonus to AC, they don’t apply against touch attacks.
An insight bonus improves performance of a given activity by granting the character an almost precognitive knowledge of what might occur. Multiple insight bonuses on the same character or object do not stack. Only the highest insight bonus applies.
A luck modifier represents good (or bad) fortune. Multiple luck bonuses on the same character or object do not stack. Only the highest luck bonus applies.
A morale bonus represents the effects of greater hope, courage and determination (or hopelessness, cowardice and despair in the case of a morale penalty). Multiple morale bonuses on the same character do not stack. Only the highest morale bonus applies. Non-intelligent creatures (creatures with an Intelligence of 0 or no Intelligence at all) cannot benefit from morale bonuses.
A natural armour bonus improves Armour Class resulting from a creature’s naturally tough hide. Natural armour bonuses stack with all other bonuses to Armour Class (even with armour bonuses) except other natural armour bonuses. Some magical effects (such as the barkskin spell) grant an enhancement bonus to the creature’s existing natural armour bonus, which has the effect of increasing the natural armour’s overall bonus to Armour Class. A natural armour bonus doesn’t apply against touch attacks.
A profane bonus (or penalty) stems from the power of evil. Multiple profane bonuses on the same character or object do not stack. Only the highest profane bonus applies.
A bonus granted because of the culture a particular creature was brought up in or because of innate characteristics of that type of creature. If a creature’s race changes (for instance, if it dies and is reincarnated), it loses all racial bonuses it had in its previous form.
A resistance bonus affects saving throws, providing extra protection against harm. Multiple resistance bonuses on the same character or object do not stack. Only the highest resistance bonus applies.
A sacred bonus (or penalty) stems from the power of good. Multiple sacred bonuses on the same character or object do not stack. Only the highest sacred bonus applies.
A shield bonus improves Armour Class and is granted by a shield or by a spell or magic effect that mimics a shield. Shield bonuses stack with all other bonuses to AC except other shield bonuses. A magic shield typically grants an enhancement bonus to the shield’s shield bonus, which has the effect of increasing the shield’s overall bonus to AC. A shield bonus granted by a spell or magic item typically takes the form of an invisible, tangible field of force that protects the recipient. A shield bonus doesn’t apply against touch attacks.
A size bonus or penalty is derived from a creature’s size category. Size modifiers of different kinds apply to Armour Class, attack rolls, Hide checks, grapple checks, and various other checks.
In general, if you wind up with a fraction, round down, even if the fraction is one-half or larger.
Exception: Certain rolls, such as damage and hit points, have a minimum of 1.
Sometimes a rule makes you multiply a number or a die roll. As long as you’re applying a single multiplier, multiply the number normally. When two or more multipliers apply to any abstract value (such as a modifier or a die roll), however, combine them into a single multiple, with each extra multiple adding 1 less than its value to the first multiple. Thus, a double (×2) and a double (×2) applied to the same number results in a triple (×3, because 2 + 1 = 3).
Note: Three doubles results in a quadruple (×4, because 2 + 1 + 1 = 4).
When applying multipliers to real-world values (such as weight or distance), the normal rules of mathematics apply instead. A creature whose size doubles (thus multiplying its weight by 8) and then is turned to stone (which would multiply its weight by a factor of roughly 3) now weighs about 24 times normal, not 10 times normal. Similarly, a blinded creature attempting to negotiate difficult terrain would count each square as 4 squares (doubling the cost twice, for a total multiplier of ×4), rather than as 3 squares (adding 100% twice).
Each ability, after changes made because of race, has a modifier ranging from -5 to +5. Table: Ability Modifiers and Bonus Spells shows the modifier for each score. It also shows bonus spells, which you’ll need to know about if your character is a spellcaster.
The modifier is the number you apply to the die roll when your character tries to do something related to that ability. You also use the modifier with some numbers that aren’t die rolls. A positive modifier is called a bonus, and a negative modifier is called a penalty.
| ————————— Bonus Spells (by Spell Level) ————————— | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Score | Modifier | 0 | 1st | 2nd | 3rd | 4th | 5th | 6th | 7th | 8th | 9th |
| 1 | -5 | Can’t cast spells tied to this ability | |||||||||
| 2—3 | -4 | Can’t cast spells tied to this ability | |||||||||
| 4—5 | -3 | Can’t cast spells tied to this ability | |||||||||
| 6—7 | -2 | Can’t cast spells tied to this ability | |||||||||
| 8—9 | -1 | Can’t cast spells tied to this ability | |||||||||
| 10—11 | 0 | — | — | — | — | — | — | — | — | — | — |
| 12—13 | +1 | — | 1 | — | — | — | — | — | — | — | — |
| 14—15 | +2 | — | 1 | 1 | — | — | — | — | — | — | — |
| 16—17 | +3 | — | 1 | 1 | 1 | — | — | — | — | — | — |
| 18—19 | +4 | — | 1 | 1 | 1 | 1 | — | — | — | — | — |
| 20—21 | +5 | — | 2 | 1 | 1 | 1 | 1 | — | — | — | — |
| 22—23 | +6 | — | 2 | 2 | 1 | 1 | 1 | 1 | — | — | — |
| 24—25 | +7 | — | 2 | 2 | 2 | 1 | 1 | 1 | 1 | — | — |
| 26—27 | +8 | — | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | — |
| 28—29 | +9 | — | 3 | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 1 |
| 30—31 | +10 | — | 3 | 3 | 2 | 2 | 2 | 2 | 1 | 1 | 1 |
| 32—33 | +11 | — | 3 | 3 | 3 | 2 | 2 | 2 | 2 | 1 | 1 |
| 34—35 | +12 | — | 3 | 3 | 3 | 3 | 2 | 2 | 2 | 2 | 1 |
| 36—37 | +13 | — | 4 | 3 | 3 | 3 | 3 | 2 | 2 | 2 | 2 |
| 38—39 | +14 | — | 4 | 4 | 3 | 3 | 3 | 3 | 2 | 2 | 2 |
| 40—41 | +15 | — | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 2 | 2 |
| 42—43 | +16 | — | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 2 |
| 44—45 | +17 | — | 5 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 |
| etc… | |||||||||||
The ability that governs bonus spells depends on what type of spellcaster your character is:
In addition to having a high ability score, a spellcaster must be of high enough class level to be able to cast spells of a given spell level. (See the class descriptions for details.)
Each ability partially describes your character and affects some of his or her actions.
Note: A creature’s ability score can never drop below 0.
Strength measures your character’s muscle and physical power. This ability is especially important for Fighters, Barbarians, Paladins, Rangers and Monks because it helps them prevail in combat. Strength also limits the amount of equipment your character can carry.
You apply your character’s Strength modifier to:
Note: Any creature that can physically manipulate other objects has at least 1 point of Strength. A creature that has no Strength score can’t exert force, usually because it has no physical body or because it doesn’t move. The creature automatically fails Strength checks. If the creature can attack, it applies its Dexterity modifier to its base attack bonus instead of a Strength modifier. Strength 0 means that a creature can’t move at all. It lies helpless on the ground.
Dexterity measures hand-eye coordination, agility, reflexes and balance. This ability is the most important one for Rogues, but it’s also high on the list for characters who typically wear light or medium armour (Rangers and Barbarians) or no armour at all (Monks, Wizards and Sorcerers), and for anyone who wants to be a skilled archer.
You apply your character’s Dexterity modifier to:
Note: Any creature that can move has at least 1 point of Dexterity. A creature that has no Dexterity score can’t move. If it can perform actions (such as casting spells), it applies its Intelligence modifier to initiative checks instead of its Dexterity modifier. The creature automatically fails Reflex saves and Dexterity checks. Dexterity 0 means that a creature can’t move at all. It stands motionless, rigid and helpless.
Constitution represents your character’s health and stamina. A Constitution bonus increases a character’s hit points, so the ability is important for all classes.
You apply your character’s Constitution modifier to:
If a character’s Constitution score changes enough to alter his or her Constitution modifier, the character’s hit points also increase or decrease accordingly.
Note: Any living creature (any creature not of the construct, deathless or undead type) has at least 1 point of Constitution. A creature that has no Constitution has no body or no metabolism. It’s immune to any effect that requires a Fortitude save unless the effect works on objects or is harmless. The creature is also immune to ability damage, ability drain and energy drain, and automatically fails Constitution checks. A creature that has no Constitution can’t tire and is thusly immune to fatigue and exhaustion. It uses its Charisma score as the basis for Concentration checks. Constitution 0 means that a creature is dead.
Intelligence determines how well your character learns and reasons. This ability is important for Wizards because it affects how many spells they can cast, how hard their spells are to resist, and how powerful their spells can be. It’s also important for any character who wants to have a wide assortment of skills.
You apply your character’s Intelligence modifier to:
A Wizard gains bonus spells based on her Intelligence score. The minimum Intelligence score needed to cast a wizard spell is 10 + the spell’s level.
An animal has an Intelligence score of 1 or 2. A creature of human-like intelligence has a score of at least 3.
Note: Any creature that can think, learn or remember has at least 1 point of Intelligence. A creature that has no Intelligence score is mindless, an automaton operating on simple instincts or programmed instructions. Such a creature is immune to mind-affecting spells and abilities, and it automatically fails Intelligence checks. Mindless creatures don’t gain feats and skills, although they can have bonus feats or racial skill modifiers. Intelligence 0 means that a creature can’t think and is unconscious in a coma-like stupor, helpless.
Wisdom describes a character’s willpower, common sense, perception and intuition. While Intelligence represents one’s ability to analyze information, Wisdom represents being in tune with and aware of one’s surroundings. Wisdom is the most important ability for Clerics and Druids, and it is also important for Paladins and Rangers. If you want your character to have acute senses, put a high score in Wisdom. Every creature has a Wisdom score.
You apply your character’s Wisdom modifier to:
Clerics, Druids, Paladins and Rangers get bonus spells based on their Wisdom scores. The minimum Wisdom score needed to cast a cleric, druid, paladin, or ranger spell is 10 + the spell’s level.
Note: Any creature that can perceive its environment in any fashion has at least 1 point of Wisdom. Anything with no Wisdom score is an object, not a creature. Only objects have no Wisdom score, and an object that has no Wisdom score also has no Charisma score. Wisdom 0 means that a creature is lapsed into a deep sleep filled with nightmares, helpless.
Charisma measures a character’s force of personality, persuasiveness, personal magnetism, ability to lead, and physical attractiveness. This ability represents actual strength of personality, not merely how one is perceived by others in a social setting. Charisma is most important for Paladins, Sorcerers and Bards. It is also important for Clerics, since it affects their ability to turn undead. Every creature has a Charisma score.
You apply your character’s Charisma modifier to:
Sorcerers and Bards get bonus spells based on their Charisma scores. The minimum Charisma score needed to cast a sorcerer or bard spell is 10 + the spell’s level.
Note: Any creature capable of telling the difference between itself and other creatures and objects has at least 1 point of Charisma. Only objects have no Charisma score, and an object that has no Charisma score also has no Wisdom score. Charisma 0 means that a creature is lapsed into a catatonic, coma-like stupor, helpless.
When an ability score changes, all attributes associated with that score change accordingly. A character does not retroactively get additional skill points for previous levels if she increases her intelligence.