The Bull of the North resides here. Advised by Sidereals, he continues a war against the Blessed Isle. This wouldn't be much of a threat, but he has an apparently inexhaustible supply of Warstriders, which he throws against opposition, and of mundane airships, which he uses for harrying and bombing. Despite these advantages, Wren has fought him to a standstill.
Further, when Wren gains a temporary advantage sufficient to drive an advance, she is continuously beset with incredibly poor fortune. When Yurgen Kaneko drives into Realm heartlands, the defense grid repels him.