SRD:Improved Whirlwind Attack

Prerequisites
Int 13, Dex 23, Combat Expertise, Dodge, Mobility, Spring Attack, Whirlwind Attack.

Benefit
As a standard action, the character can make one melee attack for every five points of his or her base attack bonus (including epic attack bonus, round fractions down).

The character cannot attack any one opponent more than once as part of this action. These attacks (as well as all other attacks made until the start of the character’s next turn) suffer a –4 penalty.

When using the Improved Whirlwind Attack feat, the character also forfeits any bonus or extra attacks granted by other spells or abilities (such as Cleave or the haste spell).

Since these attacks are made as part of a standard action the character can’t make a 5-foot step between any two of the attacks.

Normal
Without this feat, using the Whirlwind Attack feat requires a full attack action, and the character can take a 5-foot step between any two of the attacks.