Improved Critical

Improved Critical [General]

Choose one type of weapon, such as a longsword or greataxe. With that weapon, you know how to hit wear it hurts.

Prerequisites: Proficient with weapon, Base Attack Bonus +8.

Benefit: When using the weapon you selected, your threat range is doubled.

Special: You can gain Improved Critical multiple times. The effects do not stack. Each time you take the feat, it applies to a new type of weapon.

A fighter may select Improved Critical as one of his fighter bonus feats (see page 38).

Source: Player's Handbook