Greater Two-Weapon Fighting

(Masters of the Wild: A Guidebook to Barbarians, Druids, and Rangers, page 23, DnD 3.0)

[General]

You are a master at fighting two-handed.

Prerequisite

Improved Two-Weapon Fighting, Two- Weapon Fighting, base attack bonus +15, Ambidexterity

Benefit

You get a third attack with your off-hand weapon, albeit at a -10 penalty.