Increased Critical - Epic (3.5e Feat)
From D&D Wiki
Prerequisite: Base Attack Bonus +25, Proficient with weapon, Improved Critical, Great Cleave.
Benefit: When using the weapon you selected, your threat range is doubled.
Special: You can gain Increased Critical only once. The effects do stack wiht the improved critical. This effect doesn’t stack with any other effect that expands the threat range of a weapon.