Although the magic array surrounding the prison cell is very tight and advanced, it is inherent that arrays cannot be made perfect when being constructed; they will always have flaws.
Why is that? Because when constructing a magic array, you always have to leave a spot for the "array eye."
What is an array eye? The array eye is the place that activates or maintains the array's operation.
Once you have the array constructed, if you don't "charge" it, it won't operate, equivalent to a pile of useless scrap iron. Of course, it will exist in the void for a time until the spiritual power on it is fully consumed, then it will disappear.
So, if you want the array to operate or continue operating, you must "charge" it.
So here comes the question, how do you "charge" it?
It's actually very simple, just like household appliances; you need power cords to turn them on, and they must have "charging ports" or "power entry points."