Feat · Rules Tome 2.0.8 § 603.2
Charisma
Before a nearby target rolls, a successful feat check gives that roll advantage or disadvantage.
How it works
Full rule
Limited React: Before a target Character within two ranks makes a die roll, make a DC 20 Charisma check. On success, choose advantage or disadvantage for that roll.
At the table
Example
Before a nearby enemy makes a save, pass Charisma and give that save disadvantage.
Watch for this
Common mistake
Charisma must be declared before the target rolls and is Limited to once per turn.