As a reaction, which you use when you make a skill check or a saving throw or when you are hit by an attack or missed by 4 or less that you can see, you can twist fate. You make the roll with advantage or the attack against you is made with disadvantage. You can do so after the roll but before any effects of the roll occur.

If the roll already has advantage or disadvantage, you cannot apply another instance of advantage or disadvantage and you must use this before the roll to cancel out any advantage or disadvantage.