The magician appears to his surroundings as nothing in the truest sense of the word. No attention is paid to him, people bump into him on the street, but do not care. Even if he addresses someone, he is ignored. If he manages to attract someone's attention, they immediately forget about him as soon as he withdraws from them.
This spell is not a transformation of the caster, but a mass hypnosis. As a result, the caster cannot be detected even by clairvoyance spells like Recognize Life. His aura is just as visible as ever, but no attention is paid to it.
Someone who specifically searches for the caster is entitled to a Perception check in order to discover him nevertheless. If this is done with Power successes, the hypnosis effect falls off the seeker and he can perceive the caster normally again.
The caster must succeed in a test of willPower to avoid falling into a deep depression.