You slam a foe with your shield, sacrificing your armor bonus for power. You lose your armor class bonus granted by your shield until the start of your next turn. You deal 1d4 bludgeoning damage on a successful attack roll. You have proficiency on this attack roll if you have proficiency in shields. If your shield has an enhancement bonus, your damage and attack roll are increased eaually.
You can perform a shield bash as an attack with an off-hand weapon. This attack functions identically to dual wielding.
Adding shield spikes to your shield changes this damage to be piercing.
Adding a shield blade allows shield bash to do slashing or bludgeoning damage.
If using the Block variant reaction, you cannot Block in the same turn you perform a shield bash.