VIDEOS:
The first five keys
All of the gifts given to the Mane Six minus Twilight over the course of the season are revealed to be the keys to the crystal chest.
Example of:
Chekhov's Gun
Discord's ears burning
Example of:
Visual Pun
Twilight's Kingdom
Example of:
Secret Test of Character
Discord
Example of:
Face-Revealing Turn
You'll Play Your Part - Part 1
Example of:
"I Want" Song
You'll Play Your Part - Part 2
Example of:
Pep-Talk Song