The protective formation forms an invisible barrier in front of the door of the basement. This barrier can be broken with force.
Unlike the illusion that preceded it, this barrier is not paper-thin. It will require a lot of force to break it.
The time the barrier will last is dependent on the power of the intruder. A powerful intruder can poke it with a finger, while a weak intruder will spend a few minutes struggling with it.
After he was done setting up the formations, he added more things to the basement to ensure his safety.
The first thing he added was an escape tunnel that led outside the house. That way, he won't be trapped in the basement.
The second thing he added was traps between the door behind the Illusion formation and the door behind the protective formation.
There is the illusion formation, which hides a door. Behind this door is a staircase that leads to the basement. Before the door of the basement can be opened, the barrier has to be breached first.
