L Sprague de Camp's "Emperor's Fan" (short story, magic, humor): Emperor's ultimate defense against potential assassins!
This recall signal is in the form of a code. You fold the fan, & tap your left wrist, right wrist, & forehead in a certain sequence & a certain number of times. One code recalls the vanished kings, another vanished prime ministers, another vanished dragons, another vanished beggars, ... A little code book documents "all the categories of organic beings subject to the fan's power."
So we have fun as the king & sundry power usurpers use the fan, & adventures of one of them trying to reconstruct the lost code book experimentally.
Fact sheet.First published: Harry Harrison (ed)'s "Astounding: John W Campbell Memorial Anthology" (1973)
Related: Stories of L Sprague de Camp.