Alradian: the shadow invasion

it's been 2 years since the events of the last book. Alradian has married Lily, and have 2 wonderful twins, a boy and girl, each a year old, named Triston and Cynthia. Alradian has constructed a blademaster hall in malkadias capital, lochnes, and has taken on a apprentice, the young, yet haunted Charlie, a former gladiator of the slave kingdom manaria. everything is calm in the world, until a new race appears. the shades, a race of shadow people, only seen as pitch black silhouettes, invades the land. there is a prophecy that foretold this, saying only the king of ravens, the son of sorrow, the daughter of fury, and the emperor of Sun can defeat them. however, what will they lose in their quest to defeat the shades? and who are the other 3 of the prophecy?