Devastating Critical (light flail)

Type of Feat: Combat
Prerequisite: Strength 25+, Cleave, Great Cleave, Improved Critical (weapon to be chosen), Overwhelming Critical (weapon to be chosen), Power Attack, Weapon Focus (weapon to be chosen).
Specifics: Whenever scoring a critical hit with the chosen weapon, the character's target must make a Fortitude save or die instantly. Creatures who are immune to critical hits are not affected by this feat.
Use: Automatic.