Obsidian Ridge (novel)

Obsidian Ridge by Jess Lebow is the second book in the The Citadels series.

"Nothing is beyond the reach of the Obsidian Ridge.

No one has laid eyes on the Obsidian Ridge in over a century. The floating mountain is a legend, lost in the dustiest tomes… until it appears as if from nowhere over the kingdom of Erlkazar.

Driven by the madness of its master wizard, the Obsidian Ridge will destroy everything in its path until the wizard gets what he wants: the princess of Erlkazar for a bride. But deep in the tunnels of the Obsidian Ridge, a room of trophies attests that he wants a great deal more.

The citadel has hunted such quarry before."

The Year of the Leaping Frog
Somewhere over Calimshan in, a princess is taken before Arch Magus Xeries, master of Obsidian Ridge, He offers her whatever she desires if she will stay with him.

The Year of the Staff
One hundred years later in the city of Llorbauth, capital of Erlkazar, a figure known as the Claw assassinates a man named Jallal Tasca—who was planning to assassinate King Korox Morkann—and takes his brother Pello Tasca prisoner. Both men were also involved in the illicit trade of the magical drug Elixir. Pello is brought before the king, and the Claw tells the king that he will continue investigating.

The king then summons his daughter back to the throne room.