Overlord, Vol. 9 (light novel) : The Caster of Destruction

The annual war between the kingdom and the empire almost always ends in little more than a staring contest. This year, the Fresh Blood Emperor's visit to Nazarick will change everything. Ainz himself has joined the fray, which is a dark omen of the coming storm. The arrival of the absolute ruler of Nazarick means only horror and death await those who stand on what will become the most hellish battlefield anyone has seen in living memory...!