The quota for entering the Void Corridor is not easy to obtain, even large Wizard Organizations like Black Sail only hold some of the quotas.
These quotas are distributed as rewards, mostly requiring certain contributions to exchange, which demonstrates their value.
The Crawford Clan originally did not have any quotas, but to uncover the cause of Bell's death, they had to send someone in to investigate.
Initially, they applied for eligibility with the Wizard Council, but were rejected.
Later, the Crawford Clan purchased a quota from the Thorn Holy Tower to arrange for someone to enter the Void Corridor to investigate the matter.
So far, no results have been found because even Bell's body has not been located, and there's no trace of his soul.
It's quite normal not to find the body, as Duke had it reduced to ashes, so it's naturally impossible to find it.
