Parry is a reaction that is aquired through feats. When you gain parry, you unlock the following reaction
Parry(1 Reaction)
Trigger: When targetted by a melee attack.
Roll an attack against the incoming attack with your currently equipped weapon, . If you have not made an attack action that turn, it counts to your MAP. Else Parry does not count to MAP even if you made an attack that turn.
If your roll is higher than their attack roll, you stop the attack
If your parry roll is 10 or higher than their attack roll. They become off-guard