Contagious Magic
A form of sympathetic magic based on the view that things once conjoined continue to influence each other when separated; thus magic performed on a lock of hair may affect the person from whom it came.
Contagious Magic is magic that attempts to affect a person through something once connected with him or her, as a shirt once worn by the person or a footprint left in the sand; a branch of sympathetic magic based on the belief that things once in contact are in some way permanently so, however separated physically they may subsequently become.