Kitchen Raid?

Lin Wu got near the gate of the courtyard and could feel the wisp of aura that was placed on to him by the virtual interface to resonate with the formation array. 

"Huh, so this is how it recognizes the owner of a key." Lin Wu muttered to himself.

Having a key to the formation array didn't mean that anyone couldn't go in and out. But rather they would be detected and an alarm would be rung. While it could be made so that the Formation locked the courtyard completely, that function was unavailable to Lin Wu.

Lin Wu extended his spirit sense and scanned the area around the gate, only to find it completely empty.

"Why is it empty? Shouldn't there be more guard here?" Lin Wu wondered.

But then when he scanned further with his spirit sense, he discovered the reason for it.

"Oh… the range of the formation array extends beyond the courtyard and reaches the end of the street." Lin Wu understood.