Your critical hits hurt more.
Prerequisites: BA +8, Proficiency with weapon, Improved Critical Range
Benefit: With one particular weapon, add x2 to its critical hit damage. Thus, if you had a weapon with a x3 to crits, this feat would change it to a x4. You can take this feat multiple times, but its effects do not stack. Instead, it applies to a new weapon.
Special: This feat stacks with supernatural enhancements that grant a critical multiplier.