Lady Lockjaw is a member of the Ladies Court, one of Nine-Fingers' elite bodyguards and part of the Guild. She can be encountered in the Guildhall during Act Three.
Deal extra damage to a foe you have Advantage against. Also works if you have an ally within 1.5 m / 5 ft of the target and you don't have Disadvantage.
Deal an extra 1d6 damage to a foe you have Advantage against. You can also use Sneak Attack if you have an ally within 1.5 m / 5 ft of the target and you don't have Disadvantage.