The War Tides Saga, Book 4: Bore Tide

Grost and its allies lie defeated at the feet of the victorious allied armies, but also defeated is the hope to the ending of the Wars of the West. Amongst the prisoners taken at Grost are contingents of soldiers from far away and powerful realms, the Tri-Empires and the Empire of Quang among others.
Splitting their forces Queen Soon-Li leads a group of armies north, into the defeated lands of Grost and its northern allies. Meanwhile, kings Matrix and Borusa lead their forces south, through Kashem and into its southern and eastern allies, until they reach the borders of the northern Tri-Empires. Meanwhile, in the ports along the coasts of Troas, King Thorval, Jarl Arent and Prince Hillred ready their forces for a seaborne assault against the third empire, Kastenland.
What will they find as they follow the trail that leads to Ra, the fabled 'City of Wizards' and its 'Eternal Emperor'? Will the wars end as a Bore Tide rushes up the Doche River towards Ra, or will they find something else waiting for them in this never-ending conflict?