Based on what I understand, AOP cannot be fully destroyed by outside forces because it is done daily. Sure they can send a curse strong enough to penetrate but the aura is still there to blunt future blows although it might become weaker after an attack, as long as you do it daily then the energy will be returned to it's previous strength or even stronger depending on how much aop rep you do times the amount of spiritual power you have. Because like HP cobra explained there is unlimited energy out there, the only bottleneck is your own power/ability to absorb/direct/program the energy. To make this clear, two person both do app. Person A does Five breaths but is more experienced meditator. Person B does 20 breaths but is a beginner. So if person B does only Five breaths then the amount of energy might not even be enough to protect him/her. But person A because of experience and knowledge can raise/draw/direct/program energy more efficiently thus able to control and command more energy with each breaths so five breaths might just be enough, but since he is experienced the he might not even settle with just five, maybe he'll go forty plus runic vibrations plus invocation to SATAN and a lot of other methods to empower a working, might as well turn it into a formal ritual.