Partially inspired by Fear Within, Labyrinth, and the Pony Life episode the Mysterious Voice.

Short description: Spike’s missing. A trail of clues leads Twilight Sparkle and friends to a mysterious castle.

Long description: After being turned down by his friends, including Twilight, to hang out, Spike felt more lonesome and doubtful of his friendship with the ponies.

The next day, Twilight and the girls have noticed Spike has gone missing. A message was left behind, to reveal the dragon’s been taken to a castle, that’s built like a maze, with traps and riddles to test their wills.

To find their missing friend, the Mane Six are willing to take on the trials, uncover the truth about their friendship with Spike, and find him before time runs out, or he will be lost forever.

I think it’d make a thrilling story where Spike still had a disagreement with the girls, and leaves Ponyville because of it.

But it makes for a breath of fresh air, to have it where he doesn’t turn evil, or insane, because of the Mane 6’s neglect. And instead, TESTS their perseverance and determination to get him back.

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Sounds like a nice story, can’t wait to read it.

Add something related to alternate universes.
End of the test to distinguish them from him Spike from his alternatives.