The Silent Breath Redoubt is a defense-works with room for 200 that is integrated into stone – seamless natural looking entrance/exit points of 10 ton counter balanced stone vibration activated . can become airtight. Appears at a slightly different place each time, but always on the east side of The Autumn Wall – behind the lines of the Lich Lord’s minions. Sliding and grinding, a platform with war engines emerges from the stone. It is when the undead are in danger of overrunning one of the defense works on The Autumn Wall it appears. Wary the fire ball from trebuchet on platform, and ballista firing wire spinning rolls. They will climb out above dump pots of grease tar fire using claws to hold on.
They are sealed and only occupied in an emergency. Dust of ducateon bones and glass is put in all rooms. on airflow, they circulate, angry spirits stirring it up to foul lungs and eyes = seems like a disease/curse.
It’s a numbers game to them. Once the last of them are killed and their song is no more, seals up again, incinerates everything inside and resets. Each year they send about 60 now. They last about 3 months before being overrun. but easily kill 6-10x their number.
shrine, access to wall foundations for healing. travel there by vibration. must have a priest and Well of Madur they leap into to travel.