Heavy Weapon Master

You are an expert at wielding a melee weapon with the “heavy” characteristic, using its momentum empower your strikes.

When you score a critical hit with a heavy melee weapon or reduce a creature to 0 hit points with one, you can “follow through” and make one melee weapon attack as a bonus action.

Before you make a melee attack with a heavy weapon that you are proficient with, you can choose to take a penalty equal to your proficiency to the attack roll. If the attack hits, you add DOUBLE your proficiency to the attack's damage.