Li Fei did not have any intelligence network in the Northern Territory, especially within the Military Supply Headquarters.
The reason he could grasp so many details was entirely due to the 'Dream Realm'.
In the past two days, it seemed he stayed in the camp, not going anywhere.
In fact, that was just a clone he intentionally left behind.
He himself deployed the Sword State·Invisible, quietly infiltrated Shaman City, entered the Military Supply Headquarters, then entered the Dream Realm, penetrating into the subconscious of Zhang Anwu and others.
If the content was bound by the Oath Technique, or it was a deeply hidden secret in the person's heart, Li Fei would not be able to obtain information from the subconscious without alerting the person.
But the private hoarding of Replenishing Essence Elixirs had happened only in the last few days, moreover, such matters were already routine operations for Zhang Anwu and others, not considered secrets at all.