You gain the following benefits.
Luck Points.
You have a number of Luck Points equal to your Proficiency Bonus and can spend the points on the benefits below. You regain your expended Luck Points when you finish a Long Rest.
Advantage.
When you roll a d20 for a D20 Test, you can spend 1 Luck Point to give yourself Advantage on the roll.
Disadvantage.
When a creature rolls a d20 for an attack roll against you, you can spend 1 Luck Point to impose Disadvantage on that roll.