The designers of DnD didn’t want to use shields to shield bash. I DO! Let’s make that happen a different way!
When you have a shield in your off hand, you can use it as a weapon as if you were performing two weapon fighting. You do not get to normally add your Strength bonus to damage when you use this ability unless another ability would allow you to. A regular shield does 1d6 bludgeoning damage on an attack and you are considered proficient with the weapon if you have this ability.