The Twisted Citadel (DarkGlass Mountain, #2)

"The land of Ashdod has a mysterious past, and a mysterious structure in the heart of the land... Darkglass Mountain, an ancient pyramid. The Icarii Talon, StarDrifter SunSoar, wonders if Darkglass Mountain could be a StarGate, a source of Icarii power. Meanwhile, his son, Axis, is helping to lead the military might of Isembaard while its tyrant, Isaiah, is on his own lonely journey. Maximilian the king of Escator, and his estranged wife, Ishbel, ride alongside Axis... both of them obsessed with the impregnable citadel of Serpent's Nest. Also riding with Axis are the Lealfast, a peculiar race of Icarii from the frozen north. They are related in some way to the Skraelings, those terrifying creatures who can very, very quickly overrun a land and its people. But to whom do these Lealfast give their loyalty..."--Provided by publisher.