In ancient times it was said a race of warriors, hailing from an alien world once walked the ground of old Equestria.
They were called the Silver People, a race of bipeds with glimmering armor and swords that came and assisted the alicorns during a time of great peril.

But even after grand victories and countless deeds, their kingdom lasted only for two-hundred years when according to myth, they had turned to the dark path they once swore to fight.

Millennia later, Twilight Sparkle's curiosity gets the better of her, and she is fully determined to learn what drove Mankind over the edge, and their fall.

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A/N:
Daaarn this got featured!
That's amazing, thank you ALL!

Princess Luna is one night outside when she encounters an strange orb of energy.
When touching it, she is sent to a strange new world, battle-scarred and barren.
The last remains of the once-grand people now lives in underground tunnels, called the Metro.
Here, danger lurks behind every corner, mutated beasts and unknown phenonomenons.

And so, Luna must learn to adapt to the harsh Metro and if nessecary, to kill in order to survive.