As a reaction, which you use when a creature other than you within 10 meters who can see or hear you makes an attack roll, ability check, or saving throw roll, you can inspire it. The creature makes the roll with advantage. 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.
You can inspire one additional creature for each additional mana expended. The creatures must be within 5 meters of each other when you target them.