- "...although he could barely see out of it, he pointed his wand through the smashed window and started muttering incantations of great complexity. Harry heard a weird rushing noise, as though Flitwick had unleashed the power of the wind into the grounds."
- —Flitwick casts enchantments such as this one over the school[src]
Protego horribilis is the incantation to a protective spell. It is probably the most powerful version of the Shield Charm, which is used as a protective enchantment against anything approaching the protected area, and against any Dark magic, except the Killing Curse, which is unblockable with any Shield Charm and passes through it, presumably leaving holes into the magical shield. By extended use of the shield penetration spell, the magical shield could eventually be broken down.
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 the next day.
Latin Protego, "I protect", and Horribilis, "horrible , frightful, dreadful"; altogether the charm means "I protect against the horrible."
Behind the scenes
- In Harry Potter and the Deathly Hallows: Part 2, this spell is not used. However, the similarly named Protego Maxima is among the defences that are put up in the film.