Finding Spell
A friend of mine has a family spell that's been passed down for who knows how long, a spell of finding.
It always works.
My friend is from Italy originally, from a little town in the mountains north of Rome. When she was little, anything in town that went missing always got referred to her grandmother, the keeper of the spell.
She always managed to find it.
“Teach me the spell, nona,” my friend pleaded repeatedly, but she wouldn't do it. The spell has a catch, you see.
The spell only works for one person at a time. As soon as you teach it to someone else, it stops working for you.
The servant serves only one master at a time.
The decades went by. My friend emigrated to the US. Nona died. Whether or nor she passed the spell along to anyone first, my friend doesn't know.
Like a burning glass concentrating the rays of the Sun to a single burning point, magic works by the targeted application of focused power. Structuring a spell in such a way that it only works for one person at a time is about as focused as it gets.