The All War

The All War is the name of book 6. It is also one of the central cruxes of the whole of series 2, which focuses around the struggle to bring the All War to an end.
It begins with the Erayics and the Jindarians fighting one another over tensions caused by their differences in ideology. The Higharc of Eray is democratic while the kingdoms on Jindaria are monarchies. Trade disagreements and immigration fuels the rage and the two sides fight. In the background lies Usor'an, who lives in exile since the end of series 1 and seeks to regain control of his old kingdom, the Demon Empire. He plans to control the Demon Empire and use it to side with the Erayics to crush Jindaria.
At the same time, a separatist group from the Demon Empire called Demopact is making profit off the All War by selling weapons to both sides. One of the contracts on behalf of the Higharc: protect a band of mercenaries who have been contracted to kidnap Anar's son Mhaldin.
When Mhaldin is rescued, the boy betrays his family and joins Demopact. He dislikes their close relationship with the Higharc and makes Demopact think the Higharc has betrayed them by poisoning their members, killing enough to secure his place as the head of Demopact. Mhaldin then helps Usor'an become the lord of the Demon Empire. Then, side by side, Usor'an and Mhaldin unite the demons and attack Eray and Jindaria together.
The All War thus enters a new stage. With the original causes of the war forgotten, and a mutual enemy bearing down on them, Jindaria and Eray unite against Usor'an. The war thus becomes a prolonged war of attrition with the potential to last centuries.