Base Attack Bonus

The Base Attack Bonus (or BAB) is a number that represents a character or monster's skill at fighting that comes purely from his or her profession, training, and personal experience. BAB is an important part of your total attack bonus. It also affects your attack speed.

Benefits
Base Attack Bonus serves several roles in DDO:
 * It is added to all attack rolls with any weapon, including bare hands.
 * It determines the number of attacks in your attack sequence.
 * It determines player attack speed:
 * For melee weapons, attack speed increases at BAB 1, 3, 5, 10, 15, 20, and 25
 * For bows and thrown, attack speed increases with each point of BAB, and it grows much faster than for melee.
 * Several combat-related feats require a minimum BAB to unlock.

Progression
The BAB progression for players is based on their class (for creatures, on their HD), and follows one of the three following progressions:
 * +1 BAB per level, the best BAB progression, is reserved for the warrior classes (Barbarian, Fighter, Paladin, and Ranger).
 * +.75 BAB per level, the second best BAB progression, is used by the Artificer, Bard, Cleric, Druid, Favored Soul, Monk, and Rogue.
 * +.5 BAB per level, the worst BAB progression, is used by the Sorcerer and the Wizard. Epic levels also use this progression.

Fractions are dropped (rounded down). To calculate BAB of a multiclass character, first round down the BAB for each class, then add numbers together. For example, a level 3 character with one level of rogue, one level of bard, and one level of sorcerer has a BAB of 0 (floor(0.5) + floor(0.75) + floor(0.75)). A level 9 character with 1 rogue and 8 barbarian levels has a BAB of 8 (8 + floor(0.75)).

Increasing base attack bonus
Certain spells and abilities make your base attack bonus equal to character level:
 * Bladesworn Transformation
 * Divine Power spell
 * Divine Power toggle: Warpriest enhancements T5 ability
 * Madstone Rage
 * Past Life: Student of the Sword clicky
 * Tenser's Transformation spell
 * Tenser's Transformation toggle: Eldritch Knight enhancements T5 ability
 * Victory Song toggle: Warchanter enhancements level 18 core ability
 * Just Cause: Divine Crusader first innate ability

Additionally, Flurry of Blows allows a centered monk to receive a full BAB progression for all monk levels, rather than the standard 0.75.