Lucky is a passive feature provided by the Feat of the same name. You gain 3 Luck Points, which you can use to manipulate either your rolls, or an enemy's rolls.
Description
You gain 3 Luck Points, which you can use to gain 
Advantage on 
Attack rolls, 
Ability checks, or 
Saving throws, or to make an enemy reroll their Attack rolls.
Grants:
How to learn
Granted by the feats: Lucky (Feat)