Movies and Books Edit
Chamber of Secrets EditExpelliarmus first appears in Harry Potter and the Chamber of Secrets by Snape towards Gilderoy Lockhart, before Harry and Draco Malfoy get into a 'non disarming battle'. Snape demonstrates the disarming spell on the new Defence Against the Dark Arts teacher to show how to use Expelliarmus and what it does. The cast is not most powerful, although Snape is successful in disarming Professor Lockhart and defeating him in their small duel.
Prisoner of Azkaban Edit
Goblet of Fire Edit
Order of the Phoenix Edit
Learning Level-3/8. Expelliarmus is quite an easy spell to learn. The disarming spell can be used and learnt at the Hogwarts dueling club, and more commonly, in the Defence Against The Dark Arts class taught by many Professors in Hogwarts history.