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Chapter 4: Twilight Sparkle

Back in Ponyville, the changelings continue to terrorize the ponies, and Sweetie Drops races to save Lyra Heartstrings. However, Lyra refuses to flee with her best friend, calling her a terrible friend and lashing insults at her. This Lyra turns out to be a changeling, and the real Lyra arrives with Twilight to save Sweetie Drops. She and Lyra have a warm reunion, and Twilight beckons them toward the castle to take shelter. On their way to the castle, Twilight wonders how to stop the changelings when Lyra alerts her to her glowing cutie mark. Realizing she is being summoned by the Cutie Map, Twilight races to the castle.

At the castle, Twilight and Spike look at the map and see that Twilight being called to the castle itself—more specifically, the top of the castle. On the castle's highest floor, Twilight finds a door she'd never seen before, with an inscription that calls for "friendship's princess" and "two friends whose relationship has been tested by the greatest of challenges". When Lyra and Sweetie Drops catch up with Twilight, the door opens, and Twilight realizes they are the "two friends" that the inscription refers to. Through the door, the ponies discover the "Armor of Friendship", an artifact that will allow Twilight to see through changelings' disguises.

With the Armor of Friendship, Twilight soars through town and gathers up the changelings disguised as ponies.