Well for instance, the damage the shield takes does mental damage to you. I'm not saying it will make you retarded but the more damage the shield takes, the more your mind hurts. You could block a car with the shield but that could do mental damage and make the shield go out. Like getting exhausted. Like say you use the shield to block a one hit kill ability. You block the attack but the damage the shield had to take transferred to you mental and knocked you out. That's an example. Kinda like stretching your mental ability to far.