Snow falls without a trace, a passing goose leaves its call.
After any magic is used, there are traces to follow. It could be an abnormal wrinkle in space, a special scent left by a magic potion, or an illusion created in reality after the breaking of a ley line.
Of course, the most significant and clearest characteristic is the residue of magic power after the use of magic.
Just as gunpowder remains after a firearm is discharged, magic power leaves a trace of spiritual energy on or around the wizard who casts it. Many experienced hunting teams, during the Hunting Competition, have certain skills to measure this residue, thereby making precise assessments of the environment around the Hunting Ground. Organizations like Trisword conduct regular investigations that involve the measurement of magic power residue.