@Joshua
Though The Hero’s Journey applies more to Tempest than to Twilight.
The Call to Action is her losing her horn.
The Refusal of the Call is her trying to go back to playing with her friends.
Her Supernatural Aid is a horn that can shoot lightning.
Leaving her home is crossing the threshold.
The Storm King is The Shapeshifter, a character she doesn’t trust, but still needs help from.
Celestia, Luna, and Cadence are The Goddesses.
Twilight is debatably The Temptress, but with a twist. Twilight is trying to get Tempest to stray from her quest, but that would actually be a good thing.
Atonement with The Father is her fighting against The Storm King, the male character who has ultimate power over her.
In a way, she has two Deaths and Rebirths. The first is when she loses her horn and the naive, innocent Tempest dies. The second is when she sacrifices herself to defeat The Storm King, and is reborn as the kind, selfless character she once was.
The Return With Elixir is her realizing she can use her horn to create something beautiful, and the Freedom to Live is her doing a fireworks show to accompany the Celebration of The Storm King’s defeat.