Ritual Defense

You are going to make a ritual defence of your land. Unfortunately, it will be unsafe and you should think how you will defend yourself from evil.

Every ritual should be supported with defence in case if evil spirits will attack you. This ritual can go wrong if you won't defend the field activating the crystals in time. The light from activating the crystals destroys all evil around and it won't touch you for some time. Can you protect yourself from that evil skulls?