Gore or Glory

You've sharpened and cared for your horns to make them into deadly lacerating weapons. 

You gain the following benefits: 

When making an attack with your horns, you score a critical hit on a roll of 19 or 20. On a critical hit with your horns, the target must make a Constitution save at the end of each of its following turns, with a DC equal to 10 + your Constitution modifier. On a failure, the creature takes necrotic damage equal to your proficiency bonus. The condition ends after three successes or 1 minute.