Patronus

Patronus Charm is a charm that we used to against the Dementor.
It may not destroy the Dementor but it can push them far away from us.
before using this charm, you need to think about a happy memory
then try to focus on it
and then
repeat after me,
Expecto Patronum

Well, this is my patronus, hare. same with Luna Lovegood

 

Patronus also used to send message, right? in deathly hallows part 1?
patronus spread happines