Unclear; protection — repels enemies (most likely)
Repello Inimicum is a charm that, when cast in combination with Protego Maxima and Fianto Duri, conjures up an almost impregnable magical protection barrier. Bodies crossing the boundaries of the barrier disintegrate on the spot, while spells cast at it (if not of enough power to break it) create large, resonating explosions. This spell's effect is most likely seen when the charging snatchers run at the shield, and disintegrate in seconds.
This spell was cast by Charms Master Filius Flitwick to protect the boundaries of Hogwarts Castle from the Death Eater forces in the late hours of 1 May, 1998, prior to the Battle of Hogwarts that started at midnight the next day. The Death Eaters, on Voldemort's command, started bombarding the magical protection with spells, and they were ultimately brought down by a spell cast by Voldemort.
- The incantation is derived from the Latin "Repello", meaning "I drive away" and "inimicum", the accusative singular form of "inimīcus" meaning "foe" or "enemy". Altogether the incantation means "I push back the enemy".
Behind the scenes
- The concrete effect of this spell is unknown, though given its etymology it appears it was devised to repel enemies. And, in Harry Potter and the Deathly Hallows Part 2, Dementors dodged the spell, but the only spell that repels Dementors is the Patronus Charm. However it is still possible that the Dementors moved away because they were not fond of the spell (which is different from 'repelling').
- In Harry Potter and the Deathly Hallows, the protective enchantments around the grounds were summoned by Filius Flitwick, and Flitwick alone. In the second part of the film adaptation, Flitwick is joined by Molly Weasley, Horace Slughorn and two unknown teachers or members of the Order of the Phoenix to do so.
- Despite the subtitles saying Repello Inimicum, some fans still believe the casters said Cave Inimicum.
- In LEGO Harry Potter: Years 5-7, the protective enchantments around the ground are summoned by Filius Flitwick, Horace Slughorn and Minerva McGonagall.