The Vault opened in 4225 AR and provided silver and precious quartz crystals. In 4227 AR, only two years after its operation started, a deadly disease known as the chillbane fever issued from its depths. Its abused miners, Jadwiga overseers, and even the ice troll bosses began contracting the disease. The epidemic resisted the treatment of clerics brought in from Algidheart and began infecting anyone who entered the Vault. It also spread to the towns of Bleakmarch, eventually reaching Algidheart.
Queen Velikas was desperately concerned with the spread of the chillbane fever epidemic, which had already devastated the city of Algidheart. The queen's advisers or Irriseni clerics could do nothing to treat the disease. At that time a Kellid woman named Inkit Reli, enslaved in Whitethrone, presented herself to the Queen, said she was a priestess of Desna, and claimed to be able to stop the epidemic if Queen Velikas would stop raiding her homeland over the Gullik River. The Queen agreed, and Inkit managed to stop the contagion within a month.
The Queen kept her promise, but brutalized Inkit and buried her alive in the Vault, which was then sealed with strong magic. Inkit's restless spirit is said to haunt the Vault. The original source of the disease is still unknown.
Some scholars suggest that a powerful demon is imprisoned in the dark depths of the Vault. The demon is simply referred to in the texts as the "Filth", and the dreadful epidemic that almost devastated Irrisen was only a taste of the deadly blasphemies that could be unleashed.