The right to decide the method of travel before departure was a privilege only Tier Four Mages possessed. Even High-level Mages did not have it. In other words, in the Floating Sea, only Tier Four Mages were qualified to lead a team.
On one hand, Tier Four Mages were powerful enough to be considered a significant combat force in the Floating Sea, making Tier Three High-level Mages seem somewhat ordinary in comparison. On the other hand, it was because once a Mage reached Tier Four, the possibility of them being an undercover agent was practically nonexistent.
Regardless of the faction, a Tier Four Existence was a force to be reckoned with, especially a Tier Four Mage.
