Vengeful Stinger

You grow a long, wasp-like tail complete with stinger that can strike those who dare attack you. While you are under the effects of this spell, when a creature adjacent to you hits you with a melee attack, you can make an attack of opportunity with your stinging tail, even if your opponent's attack would not otherwise provoke an attack of opportunity. You must otherwise be eligible to make an attack of opportunity to use this ability. The attack is made with your full attack bonus, and with a +2 sacred bonus on the attack roll. The stinging tail is considered a light weapon with a critical range of 19-20/×2. On a successful hit, the target takes 1d8 points of damage plus an amount of damage equal your Strength modifier and must succeed at a Fortitude save or it takes 1d4 points of Dexterity damage. This poison damage is also modified on a confirmed critical hit.