Patronus Charm

A Patronus is a kind of anti-Dementor. It exudes "hope, happiness, [and] the desire to survive"[HP3].

The Patronus Charm is an immensely difficult spell to perform, being well beyond Ordinary Wizarding Level. The incantation is Expecto patronum; however, the incantation itself is not enough. The caster must also concentrate on a very happy thought. Corporeal Patronuses have a shape specific to the caster.

Patronuses of the characters

 * Harry Potter &mdash; stag
 * Hermione Granger &mdash; otter
 * Ron Weasley &mdash; Jack Russell terrier
 * Cho Chang &mdash; swan
 * Albus Dumbledore &mdash; phoenix
 * Nymphadora Tonks &mdash; wolf