When another creature damages you with a melee attack, you can use your reaction and expend one superiority die to reduce the damage by the number you roll on your superiority die + your Dexterity modifier.
When you hit a creature with a weapon attack, you can expend one superiority die to attempt to disarm the target, forcing it to drop one item of your choice that it's holding. You add the superiority die to the attack's damage roll, and the target must make a Strength saving throw. On a failed save, it drops the object you choose. The object lands at its feet.
As a bonus action, you can expend one superiority die and make a ranged attack with a weapon that has the thrown property. You can draw the weapon as part of making this attack. If you hit, add the superiority die to the weapon's damage roll.