Editing Dungeons & Dragons 3rd Edition (section)

==System==
===The Core Mechanic===
3rd edition introduced the now ubiquitous "[[d20 System]]", where almost every action with a chance of failure is resolved by rolling a d20, applying relevant modifiers, and comparing the result to a set difficulty (or, in some cases, another character's roll) to determine success, referred to by the system as the "Core Mechanic". For example, a fighter attempting to hit a monster with his sword rolls a d20 and may add his Base Attack Bonus, Strength bonus, relevant Weapon Focus boni, magical enhancements, etc. with the objective of beating his opponent's Armor Class. Rolling equal to or over the target's AC means he has successfully hit and gets to deal damage. In a similar vein, a rogue attempting to pick a lock rolls a d20 and adds his skill ranks, dexterity bonus, any relevant skill boni from feats, modifiers depending on the quality of his equipment, etc. in an attempt to beat the target DC (Difficulty Class) of the lock.

This was generally regarded as a significant improvement on the systems used in 1e and 2e, where many different parts of the game were governed by vastly different mechanics. Restructuring the game around the single core mechanic made gameplay much simpler and easier to pick up for new players.

===Characters and Creatures===
Characters and creatures in the system are structured around Hit Dice and ability scores, wherein boni and traits from various hit dice are stacked together and combined with modifiers derived from the base ability scores to determine the other statistics of the entity. For example, a 2nd level Cleric/3rd level Fighter would have a +1 BAB for his two cleric hit dice and a +3 BAB for his three fighter hit dice, combining to give him a total Base Attack Bonus of +4, which would then be modified by other abilities such as strength or dexterity to determine his overall bonus when making an attack. The hit points granted to him by each of those hit dice would be added together and modified by the constitution score to determine his overall hit point total, and so on.

Almost all entities have six ability scores: Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma - that describe basic qualities of their character. The human average ability score, as the baseline from which all other ability scores are referenced, is 10 or 11. Ability scores higher than this grant boni to their relevant checks, and lower than this impose penalties. Every two points of score results in a +1 modifier, such that a score of 8-9 is a -1 penalty, 10-11 is +0, 12-13 is +1, and so on. Different races generally have boni and penalties to some ability scores to represent how they differ to humans; for example, graceful but frail elves have a +2 to their Dexterity (giving them an extra +1 bonus to Dexterity-linked checks) but a -2 penalty to their Constitution, whereas stout but surly dwarves receive a +2 to their Constitution but suffer a -2 to their Charisma.

In general, having any ability score reduced to 0 (by magic or other effects) results in incapacitation or death; a 0 Str or Dex character is unable to move himself, a 0 Con character is dead, and a 0 in a mental ability stat results in a coma. Some entities are lacking certain abilities entirely, a situation explicitly different from having a 0 in the stat: for example, a mindless magical construct that cannot think for itself both has no constitution score, as it is not a living being and is not subject to poisons, diseases, and other such things as living beings are; it also has no intelligence score, as it is generally incapable of making its own decisions and instead acts only on the orders given to it by its master.

Everything also fits into size categories, which describe how big or small they are. In ascending order, the categories are Fine, Diminutive, Tiny, Small, Medium, Large, Huge, Gargantuan, and Colossal. A creature's size category modifies its Armor Class and attack bonus (a target relatively larger than you is easier to hit), and determines the damage of its natural weapons and its space and reach. Don't think of your space as the area you occupy, otherwise you start thinking of ten-foot-wide horses; rather, think of it as the area you ''control''. How close do you want to get to a guy swinging a longsword, anyway?

===Playable Base Classes===

Remember when we said there were 54 base classes? Here they are, and what books they're from.

*[[Archivist]] (Heroes of Horror)
*[[Ardent]] (Complete Psionic)
*[[Artificer]] (Eberron Campaign Setting)
*[[Barbarian]] (PHB)
*[[Bard]] (PHB)
*[[Beguiler]] (PHB II)
*[[Binder]] (Tome of Magic)
*[[Cleric]] (PHB)
*[[Crusader]] ([[The Book of Weeaboo Fightan Magic]])
*[[Divine Mind]] (Complete Psionic)
*[[Dragonfire Adept]] (Dragon Magic)
*[[Dragon Shaman]] (PHB II)
*[[Dread Necromancer]] (Heroes of Horror)
*[[Druid]] (PHB)
*[[Duskblade]] (PHB II)
*[[Erudite]] (Complete Psionic)
*[[Factotum]] (Dungeonscape)
*[[Favored Soul]] (Miniatures Handbook, reprinted in Complete Divine)
*[[Fighter]] (PHB)
*[[Healer]] (Miniatures Handbook)
*[[Hexblade]] (Complete Warrior)
*[[Incarnate]] (Magic of Incarnum)
*[[Knight]] (PHB II)
*[[Lurk]] (Complete Psonic)
*[[Marshal]] (Miniatures Handbook)
*[[Monk]] (PHB)
*[[Ninja]] (Complete Adventurer)
*[[Paladin]] (PHB)
*[[Psion]] (Expanded Psionics Handbook)
*[[Psychic Warrior]] (Expanded Psionics Handbook)
*[[Ranger]] (PHB)
*[[Rogue]] (PHB)
*[[Samurai]] 1 (Oriental Adventures)
*Samurai 2 (Complete Warrior)
*[[Scout (D&D)|Scout]] (Complete Adventurer)
*[[Shadowcaster]] (Tome of Magic)
*[[Shaman]] (Oriental Adventures)
*[[Shugenja]] (Oriental Adventures, reprinted in Complete Divine)
*[[Spirit Shaman]] (Complete Divine)
*[[Sohei]] (Oriental Adventures)
*[[Sorcerer]] (PHB)
*[[Soulborn]] (Book of Incarnum)
*[[Soulknife]] (Expanded Psionics Handbook)
*[[Spellthief]] (Complete Adventurer)
*[[Swashbuckler]] (Complete Warrior)
*[[Swordsage]]  ([[The Book of Weeaboo Fightan Magic]])
*[[Totemist]] (Book of Incarnum)
*[[Truenamer]] (Tome of Magic)
*[[Warlock]] (Complete Arcane)
*[[Warblade]]  ([[The Book of Weeaboo Fightan Magic]])
*[[Warmage]] (Miniatures Handbook, reprinted in Complete Arcane)
*[[Wilder]] (Expanded Psionics Handbook)
*[[Wizard]] (PHB)
*[[Wu Jen]] (Oriental Adventures, reprinted in Complete Arcane)

There are some other bullshit classes too, like several that are only available to NPCs, some from third-party sources, one that you can only be when you're dead, etc. but these are the canonical 54 classes from first-party publications that player characters can take at first level.