Disillusionment Charm

The Disillusionment Charm is a spell that is used to hide something. This spell causes the object to become a kind of chameleon, taking on the appearance of whatever is behind it. It is typically used to hide magical creatures or objects from Muggles. Mad-Eye Moody cast a Disillusionment Charm on Harry Potter to protect him during the trip from Privet Drive to Grimmauld Place.

When a Disillusionment Charm is cast on a person, the caster raps their wand on the top of the subject's head. Then, it feels as if the caster has broken a raw egg on top of the subject's head. There may or may not be a nonverbal incantation.

The spell is also the most common way to create an invisibility cloak. It is possible to create such a powerful Disillusionment charm that you are completely invisible, as proved by Lord Voldemort and Albus Dumbledore.

Owners of Hippogriffs are required by law to cast a Disillusionment Charm on their creature every day to prevent Muggles from seeing them.

Etymology
"Disillusion" means "to remove an illusion", which is rather strange, considering the effect of the Disillusionment Charm is to create an illusion, not remove one. This may relate to the fact that the spell is often used to make magical creatures places and objects (things muggles might think to be illusions.) disappear from view.

Appearances

 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Deathly Hallows
 * Fantastic Beasts and Where to Find Them