When Matt returned to his room, he created several icy inscriptions to protect the room and prevent information from leaving.
He wanted to form a connection with the Spirit World, the connection the Spirit of Destiny granted to him.
According to her, this kind of deep connection should not be discovered by anyone, spirits or humans. And she spoke to him sternly about avoiding, at any cost, the spirits of the Supreme Castle from knowing about it.
That Supreme Castle governs the entire Spirit World, so Matt had to be careful in a place with so many spirits everywhere. Also, they couldn't know because this inscription breaks the rules of the Spirit World.
When he found out, he was surprised, for he did not expect her to give him such an amazing inscription. That was when he realized that this girl, although she looked tender, could be very bold and liked to take some risks as long as they did not break the laws of fate.