Consciousness is a complex thing. There is much to be learned about soul dynamics and the astral realm. Many people are aware of the idea of a spiritual entity or angels etc. but many are not familiar with the idea of thought-form beings. It is not something that is necessarily commonly referred to even when studying things like hermetic principles.

but if you dig deep enough into any esoteric science or spirit science, you will find the topic, though it will be often referred to with a different title. Thought form entities are referred to by many different names such as : eidolon, egregore, miasma, tulpa (tibetan tulpa), and probably even more. If you are hearing voices in your head spiritual beings or negative entities may not be the cause. It may simply be thought form beings. what makes a tulpa supernatural? well that may just be that they are not physical so people view them that way.

Thought forms are powerful, its more about knowing how to handle thought form beings than it is about spiritual protection or using a mantra to protect you from negative energy, psychic protection from negative entities is almost a different conversation altogether. Thought forms and the beings created by them operate in a different way.