Parrying
Parrying has long played a relevant role in combat fiction, and these rules explicate how it can be done in this game.
Parrying: Parrying is a new skill that uses the ability that you use your weapon with.
Prerequisites: To use the features below, you need to wield a melee weapon that you are trained with.
Parry: You can use your Reaction to try to parry a melee attack that you can see and that targets you. Make a Parrying check contesting the attack roll. If the result is at least as high as the attack roll, you successfully parry, reducing the attacks damage by your weapons Parrying Power.
When trying to parry a critical hit, you roll with Disadvantage.
When rolling a natural 20 on your Parrying Check, the Parrying Power is doubled.
Parrying Power: A weapons Parrying Power is equal to the maximum damage it can deal on a normal hit. This includes all temporary damage bonuses as well.
For example, a normal rapier deals damage equal to 1d8 + your Strength or Dexterity modifier, so its Parrying Power is equal to 8 + your Strength or Dexterity modifier. If it is also transmuted by the spell Elemental Weapon, which increases its damage by 1d4, its Parrying Power is further increased by 4.