As Magicians we are likely to come under attack by lesser Spirits, Parasites or even other witches from time to time. This is why it’s important to have a Spirit as a protector to help you in this area especially as a beginner.
This Spirit can be an Archangel, Archdemon or even a Pagan Deity. Even a Thoughtform.
It seems very beneficial as they can negate the attack and then deal with the attacker as they wish.