Kuzunoha had been confined in this chamber since the Seventh Celestial War.
In said war, she had poured almost everything she had into an attack spell, effectively ending the war entirely: erasing the enemies, and sealing away the ancient horrors that were among the enemies.
However, the cost for that was catastrophic. Her life force began to unravel, depleting into the void. She was going to die, as she couldn't control the immense flow of magical energy which, at that time, ravaged her being.
But her co-wives—Medline, Kumai, Tanuko, Asherah, Khanna—and the kingdom's greatest mages intervened: they wove layer upon layer of enchantments into this particular chamber, successfully saving her life.
The blue mist swirling around wasn't just a fancy feature; it was basically a life-support system, manually regulating her magic so she wouldn't simply fade away, or worse, blow up and take half the continent with it.
Anyway, even the price for that, her survival, was also expensive.
