Bull-worked Shield

This hefty shield is inscribed with an embossed bull rearing up on the face. 

Once during combat a character wielding the shield can use their action to make a slam attack with the shield. Successfully hitting with the shield causes the bull to come to life and rams into the target doing moderate damage and pushing the target back 10 feet and requires a successful stamina/constitutional check to prevent getting knocked prone. The wielder of the shield is slid back five feet from the impact. 

Image by 13smok from Pixabay