Parry this you filthy casual.

If a melee weapon attack against you misses by 3 or 4 points, roll 1d20 and if the roll is 15 or higher then you can perform 1 attack of opportunity against only the attacker if they're within your weapon's attack range.  There is no way to increase and/or reroll the roll from this feat. Prerequisite(s): Strength must be 17 or higher. Character must also be carrying a shield when using this.