The Sieving Veils.
It was a Dare!
And one that was as clear as day.
Angry and insulted as San was, he could not help but praise Hal in his mind.
First Hal had done something that made the whole Mansion seem devoid of Astral energy which normally should have made the Plebeians overconfident that all was well but because Hal was already a known Runemaster, the Effect was not the same and it was only glaringly suspicious and made the Plebeians even more cautious.
To an avid observer, Hal's plan of surprise was ruined because of this but San could tell that this was the effect Hal had wanted.
Because of how suspicious it was, San had decided to send in those he considered expendable due to the abundance of Cosmic Pearl realm cultivators as opposed to Cosmic Armament realm cultivators who were far more scarce and valuable.