Devastating Critical

Type: Epic
Sources: Draconomicon
Epic Level Handbook

Choose one type of melee weapon, such as a claw or bite. With that weapon, you are capable of killing any creature with a single strike.
Prerequisite: Str 25, Cleave, Great Cleave, Improve Critical (chosen weapon), Overwhelming Critical (chosen weapon), Power Attack, Weapon Focus (choose weapon).
Benefit: Whenever you score a critical hit with weapon you have chosen, the target must make a Fortitude save (DC 10 + 1/2 your HD + your character level + your Str modifier) or die instantly. (Creatures immune to critical hits can't be affected by this feat.)
Normal: You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new weapon.