Game mechanics (Dungeons & Dragons)

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In the 3rd edition Dungeons & Dragons role-playing game, game mechanics and die rolls determine much of what happens.

1 Ability scores
2 Armor Class
- 2.1 3.0 and 3.5 Editions
3 Attacking
4 Hit points
5 Saves
- 5.1 Advanced Dungeons & Dragons(pre-d20 system)
- 5.2 3rd Edition
6 Skills
7 Feats
8 References

[edit] Ability scores

For general information on this topic, see Statistic (role-playing games).

All characters have six basic statistics:

Strength (STR): Strength is a measure of muscle, endurance and stamina combined. For purposes of relating this skill to some reality, it is assumed in-game that a character with a strength of 3 is able to lift a maximum of 30lbs whieght above his head in a military press, while a character with a strength of 18 will be able to press 180lbs in the same manner.
Dexterity (DEX): Dexterity encompasses a number of physical attributes including hand-eye co-ordination, agility, reflexes, precision, balance and speed of movement. A high dexterity indicates superiority in all the above attributes, while a low dexterity may well indicate that one os these attributes is superior, but that the others are very poor. Dexterity affects characters with regard to initiative in attack, the projection of missiles from hand or other means, and in defensive measures. Dexterity is the ability most influenced by outside influences (such as armor).
Constitution (CON) Constitution is a term which encompasses the character's physique, fitness, health and resistance to disease and poison. The higher a character's Constitution, the more hit points that character will have. Unlike the other ability scores, which knock the character unconscious when they hit 0, Constitution will kill a character when it reaches 0.
Intelligence (INT) Intelligence is similar to IQ, but also includes mnemonic ability, reasoning and learning ability outside those measured by the written word. Intelligence dictates the number of languages a character can learn and the number of spells a Wizard may know.
Wisdom (WIS) Wisdom is a composite term for the characters enlightenment, judgement, wile, willpower and intuitiveness. Wisdom alters the chance of saving against a magical attack, and dictates the power of a Cleric's or Druid's spells.
Charisma (CHA) Charisma is the measure of the character's combined physical attractiveness, persuasiveness, and personal magnetism. A generally non-beautiful character can have a very high charisma due to strong measures of the other two aspects of charisma. It is important to all characters, but especially so to Bards and Sorcerers, as it determines their spellcasting abilities. It also determines the number of henchmen a character is able is able to retain and their loyalty.

An ability score is a natural number, with a value of 10 representing average ability. Each score has a modifier (mod) associated with it that is equal to half of X−10 (where X is the ability's score), rounding down. So, for example, an ability score of eight, two lower than ten, would mean a modifier of −1, while an ability score of 17, 7 above ten, means a modifier of +3 (7 = 3 × 2 + 1). This modifier is added to the appropriate dice rolls. For example, the strength mod would be added to the damage dealt by a sword, the dexterity mod to Armor Class (see below) as the character's ability to dodge attacks, and the charisma mod to an attempt to smooth-talk a merchant.

There are creatures that lack certain ability scores (undead, for example, have no constitution). These are called nonabilities and affect how that creature is treated by certain spells and effects. The aforementioned undead, for example, are immune to almost anything that requires a Fortitude save, unless it can also affect objects. This is not the same as having a score of zero.

There are several methods of determining a character’s initial ability scores during character creation (Dungeon Master's Guide, p. 169):

Rolling dice: This is the standard method. For each ability score, the player rolls 4d6, and adds the three highest values, resulting in scores ranging from three to eighteen.
Predetermined array of scores: Less random, but inflexible.
Point buy: In the point buy system, a player has a certain number of points to spend on their ability scores. The more powerful the characters are intended to be, the more points will be available to the players. (Characters are usually more powerful for a more difficult game.) Possible ability scores range from eight to eighteen, and each score has a certain point cost affixed to it, where higher scores tend to cost more points per level than lower ones.

[edit] Armor Class

Armor Class (AC) is a rating used to determine how difficult it is to damage a creature/character. It is based on several factors such as a creatures natural aversion to physical injury, magical enhancements, and any protective garments worn.

[edit] 3.0 and 3.5 Editions

$A C = 10 + [A r m o r] + [S h i e l d] + [D e x] + [S i z e] + [N a t u r a l] + [D e f l e c t i o n] + [M i s c]$

Armor - a number indicating the effectiveness of the armor worn by the character. Leather armor will give a smaller bonus to AC than full plate will. Armor can be enchanted to provide a greater bonus to AC.
Shield - a number indicating the effectiveness of the character's shield. A small shield or buckler will give a smaller bonus to AC than a larger shield will. Shields, also, can be enchanted to boost their AC bonus.
Dex - Dexterity modifier (see ability modifiers, above). Indicates the character's ability to dodge attacks. If the character is wearing heavy armor that hampers their movement, they can only add a certain amount of their dexterity to their AC, because they are less able to dodge.
Size - a number indicating how hard they are to hit because of their size. Bigger targets are easier to hit, and smaller targets are harder to hit; the smaller the character (in terms of size categories), the bigger a bonus they get to AC. The larger the character, the greater the penalty.
Natural - a number indicating the effectiveness of the character's natural armor (hide, thick fur, scales), if any, at stopping attacks.
Deflection - a number indicating the effectiveness of any number of effects, if any, that make attacks on the character veer off course.
Misc - any bonuses or penalties to AC not covered in the other categories; includes spells and non-armor/shield magic items.

An attacker must roll higher than or equal to his opponent's AC to score a hit with a weapon/spell.

Touch AC: how difficult it is to touch the character with an attack. An attack may clank harmlessly off armor (not dealing damage) but still hit the defender; touch AC is a character's armor class, disregarding armor, shield, and natural armor bonuses (because armor, natural armor, and shields do not make coming into contact with the character any easier or more difficult). Such a touch could cause a magical effect to affect the defender, for example.

Incorporeal touch AC: Not listed on the character sheet or mentioned often, this AC type is a measure of how difficult it is for a ghost or other incorpreal creature to strike the character. As its name indicates it is similar to Touch AC, as an incorpreal creature may reach through armor and shields. Generally, the only time this is different than standard touch AC is if the character as a force-effect contributing to armor, as incorpreal creatures may not pass through force. Examples of force effects include the spells mage armor and shield.

Flat-footed AC: how difficult it is to hit the character when they are surprised and unable to react to an attack (that is, unable to dodge). This is the character's AC, disregarding dexterity (because the character can't dodge). While most characters are unable to effectively dodge attacks when they are surprised, some are never considered flat-footed because they are considered to be continually aware of potential attack.

[edit] Attacking

When a character makes an attack, a 20-sided die is rolled and a certain number is added to determine success/failure.

The number added to the die roll is actually several different modifiers combined, coming from different places. These modifiers include the character's proficiency with the specific weapon and weapons in general, the quality of the weapon (superior craftsmanship or magical enhancements), the modifier of the ability associated with the weapon (strength for melee, or close-quarters, weapons, and dexterity for ranged weapons), magical effects improving/hampering the character's ability to attack, and any special experience the character has fighting a certain foe. If the dice roll, plus all applicable modifiers, is higher than the defender's armor class (see above), then the attacker hits the defender and can proceed to the next step, determining damage.

If the attacker hits the defender, she proceeds to determining damage. A certain die is rolled, depending on the weapon being used; the more powerful the weapon, the more damage it is capable of doing, and the higher (more-sided) its damage die will be, for a higher possible damage roll. To this damage roll, modifiers are added, including strength bonus (melee weapons only), weapon quality, and magic affecting the attacker. The damage roll, plus all applicable modifiers, is deducted from the defender's hit points (see below).

Should a character roll a natural 20 on a die roll, the hit is a critical threat. He rolls again, and, if this next roll shows a hit, he has scored a critical hit (crit for short) and deals extra damage, depending on the weapon (anywhere from twice the damage to four times the damage). For some weapons, the player need not roll a natural 20; a 19 to 20 or a 17 to 20 will do.

[edit] Hit points

Hit points (HP) are a measure of a characters vitality or health; they are determined by the character's class (certain occupations breed hardier people) or race, and constitution score. Hitpoints are reduced whenever a character takes damage. When a character is reduced to 0 hit points, he drops to the floor, conscious but unable to take more than one action per round or move at more than half speed, additionally, certain actions can cause the character to drop from 0 to -1. When a character is reduced to negative hit points, he falls unconscious, and dies when his hit points drop to -10 or less. A "dying" character (one with negative hit points) must also "stabilize" or lose one hit point per round until death; each round there is a 10% chance to stabilize (the player must roll 10 or lower on the percentile dice).

In online communities, over IM, etc., hit points is often used as one word, hitpoints, for ease of typing; it's the same thing.

[edit] Saves

Certain situations give characters the chance to avoid special types of danger or attacks. These chances are called Saves or Saving Throws. A saving throw is made when a character would come to harm from extraordinary means such as: poisons, and things magical in nature.

[edit] Advanced Dungeons & Dragons(pre-d20 system)

In basic, first, and second editions of Advanced Dungeons and Dragons, saves were made against whatever effect would have happened to the target. For example, a player facing a "Fireball" spell would have to save against the spell itself, while a player targeted from any instant-death effects would have to make a saving throw to prevent being killed.

[edit] 3rd Edition

There are three types of save, fortitude, reflex, and will. Each save requires a d20 roll with bonuses from the character's "base save" due to class levels, one key ability, and miscellaneous modifiers (such as feats or magical effects).

Fortitude: This save is often used against things like poison and disease. The key ability of a fortitude save is constitution.
Reflex: This save is often used when making trying to avoid things the character may not expect, like a trap. The key ability of a reflex save is dexterity.
Will: This save is often used when resisting charms and compulsions. The key ability of a will save is wisdom.

[edit] Skills

For general information on this topic, see Statistic (role-playing games).

Dungeons and Dragons, starting with the third edition of the game and continuing to present, has many skills that characters may train in. Characters gain skill points for buying skill ranks based on class, level, and intelligence. Some skills can only be taken by certain classes, such as Read Lips or Animal Empathy. These skills are called exclusive skills. Others can be used even if the character has no ranks in that skill (i.e., is not trained in that skill).

A skill check is always a d20 roll, with bonuses from the number of skill ranks, the skill's key ability, and any miscellaneous modifiers (from spells or racial abilities, for instance). Sometimes, a skill check may be aided by favorable circumstances (such as you brandishing a weapon while using Intimidate) or hampered by unfavorable circumstances (such as using improvised tools to pick a lock).

An example of a skill is Search, which is Intelligence-based; an example of a miscellaneous modifier which could be applied to search is the +5 competence bonus for a character wearing the "Goggles of Minute Seeing". Other skills include Diplomacy (CHA), Escape Artist (DEX), Swim (STR), various Knowledge skills (like Knowledge (Arcana) or Knowledge (Local)) (INT), Spot (WIS), and Concentration (CON).

A "check" is successful when the roll is higher than or equal to the difficultly class (DC) of the task. Usually, the Dungeon Master sets the DC. Sometimes the DC is set by the result of something else's check, this is an "opposed check". An example of an opposed check is spot against hide: the character is trying to see something else that is hidden.

[edit] Feats

Main article: Feat (Dungeons & Dragons)

Feats were introduced in the third edition of Dungeons and Dragons.

A feat is an ability that is learned and then used whenever it is befitting. You don't buy feats; you learn them as you progress in levels. If you don't have a feat or don't meet the prerequisites for a feat, you can't use it.

Feats are divided into several types, such as Metamagic and General. These types tell you which classes would be best suited for using a specific feat, for example, Metamagic feats work best when used by spellcasters, such as wizards.