Thread:LostGod2000/@comment-27818776-20140524042655/@comment-6554265-20140524223849

Well, the Mane 6 needed to open this box to defeat Tirek, a box with 6 keyholes. Throughout the season, the Mane 6 gain 5 keys on their journeys, and in the finale Twilight is the only one without a key. Since Tirek gave Discord the medallion before he betrayed him, Discord gave Twilight the medallion as a token of true graditude, unlike Tirek's false graditude. It turns out the medallion IS Twilight's key, and she uses it to open the box. So I'd say it's a plot device, because it has no deep back story and came out of no where.