Fantasy Literature

Ron uses the Wingardium Leviosa charm to levitate the troll's club and knock it out, saving Hermione. This is the levitation spell taught in Charms class that Ron struggles with initially. Hermione is trapped in the bathroom with the troll during Halloween.

Harry uses Gillyweed, a magical plant provided by Dobby (in the book) or Neville (in the film), to grow gills and webbing to breathe and swim underwater.

Dumbledore bequeaths his personal copy of The Tales of Beedle and the Bard to Hermione, which contains clues about the Deathly Hallows.

Hermione founds S.P.E.W. (Society for the Promotion of Elfish Welfare) to advocate for the rights of house-elves.

Barty Crouch Jr. uses Polyjuice Potion to impersonate Alastor Moody throughout the school year to manipulate the Triwizard Tournament.

Luna Lovegood's Patronus takes the form of a hare (often referred to as a rabbit).

Voldemort uses Lucius Malfoy's wand during the Battle of the Seven Potters because his own wand and Harry's share the same core, causing a connection effect.

Harry Potter marries Ginny Weasley, as revealed in the epilogue of the final book.

Severus Snape reveals himself as the Half-Blood Prince, a nickname he created based on his mother's maiden name, Prince.

Severus Snape kills Dumbledore at the end of the sixth book, acting on Dumbledore's own secret instructions.

Cedric Diggory is killed by Peter Pettigrew on Voldemort's orders at the end of the Triwizard Tournament.

Tom Marvolo Riddle is the birth name of Lord Voldemort, which he rearranged to spell 'I am Lord Voldemort'.

Harry's first broomstick is the Nimbus 2000. The option 'Nimbus 200' appears to be a typo for 2000.

Rachel is not a member of the Weasley family in the Harry Potter series.