The Changing Season; rogue Unseen Court member.
According to Asrabey Varal, an emissary from the Court, Ekossigan (one of the six high members of the Court’s leadership) has grown enraged by the industry in Flint, and has come to the Waking world to do harm upon the city. Though he is aided by a group of gremlins, his actions are not condoned by his peers, and they have invoked the Rite of Kelland’s Tribute to demand help in slaying him to preserve the peace. In the Court’s words, “One season slain for one war unfought.”
Hugo dealt the killing blow, preventing the mad fey from killing a whole orphanage’s worth of children, but not before leaving the party with his cryptic prophecy.