Within the world of Black Clover, there's no shortage of magically gifted people. The Clover Kingdom puts all of its best and brightest to work within the Magic Knight Guilds, assigning them to safeguard the citizens from threats both domestic and foreign. Every mage is a member of one of the nine guilds, each with a different leader and work ethic.
Source:https://www.cbr.com/black-clover-magic-knight-guilds-ranked-best/