Slayer (Fallout Supplement)
From D&D Wiki
You are Slayer, you are Strong, you have a tendency to decapitate people.
Prerequisite: BAB +16, Strength 16, Dexterity 18, Combat Martial Arts, Improved Combat Martial Arts, Advanced Combat Martial Arts
Benefit: You gain a +6 bonus to confirming critical hits with melee and unarmed attacks.