The highly anticipated prequel to Disney's "The Lion King" is set to release on Dec 20 and a new trailer has fans buzzing. Along with a glimpse at the stunning animation and epic storytelling, the D23 trailer also revealed the star-studded cast, including Aaron Pierre as Mufasa and Beyoncé's daughter Blue Ivy Carter as Kiara. Set before the events of the original film, "Mufasa: The Lion King" promises to take audiences on an emotional journey.