Trap

He quickly finished the letter, handing it to Kane. Kane had done this many times, so he didn't need any explanations at all.

The next morning Kane waited at the post office with Void Step active. The system that the two of them come up with involved putting the envelope meant for Guildmaster Bradt at the of the letter stack of the postman's carriage.

This way they didn't need to register. Rui was not foolish enough to send letters following the systematic protocols in place. That would give him away pretty easily. Guildmaster Bradt merely needed to identify the individual who posted a letter on the same day that he got a letter from the Voider, and he would have a small and manageable list of suspects for the Voider's identity.

Once he saw Kane or Rui on the list, it would mostly be game over since the two of them would probably be the only Martial Squires on the list.