summoner

summon +‎ -er

summoner (plural summoners)

1. One who summons or evokes, particularly in legal contexts.
2. (historical) An apparitor; An officer of an ecclesiastical court whose job it was to deliver a summons to an offending member of the diocese.
3. A small bell for summoning an employee to provide service.
   • 2016, Amor Towles, A Gentleman in Moscow, →ISBN, page 119:

     And as they change, they set into bright relief not only outmoded honorifics and hunting horns, but silver summoners and mother-of-pearl opera glasses and all manner of carefully crafted things that have outlived their usefulness.

• resummon