This is a renegade branch of the Vanguard. They are displeased with the path the Vanguard has taken lately and have started their own war against the Rikti...and the rest of the Vanguard. Their actions aren't supported by the Vanguard Sword's commander, Gaussian, nor by the Vanguard's leader, Lady Grey. They don't spawn in any outdoor zone and they can be fought only during the Story arc The Red and the Black from Gaussian.