Improved Devastating Strike
The fury and power channeled through your attack is enough to kill a lesser being outright.
Prerequisite: Devastating Strike, Vital Strike, base attack bonus +13.
Benefit: Whenever you use Vital Strike, Improved Vital Strike, or Greater Vital Strike, you gain a bonus on attack rolls to confirm a critical hit equal to the bonus on damage rolls you gain from Devastating Strike.
Source: Ultimate Combat, p. 105