Tide of the Forsaken

Modern archaeologist Kaelen is transported to Atlantis, where he becomes a powerless illegitimate son framed for murder. After slaying an abyssal beast in the arena and tearing up his annulment decree, he is exiled by Poseidon to a frozen city. There he awakens a dragon mark, allies with the sealed dragon Vaelith and the war goddess Athena, and leads oppressed commoners to seize energy, build farms, and fight the temple legions.