Cave inimicum

Cave Inimicum is a charm which was used by Hermione Granger in 1997 to protect the tent she shared with Ron Weasley and Harry Potter.

Etymology
Cave Inimicum is a Latin phrase which translates to "beware of the enemy".

Appearances

 * Harry Potter and the Deathly Hallows

Behind the scenes

 * Whilst the true effect of this spell is unclear it is possible that it serves as some sort of early warning system for approaching enemies, similar to the Intruder Charm.

Cave inimicum