Trolls and dragons stalk the plain
Seek for mischief they may wreak
Hush now child, they seek in vain
We are gentle, but not weak

When the night seems cold and frightening
And you know not what to do
They will be there, fast as lightning
So no harm can come to you

Do not dread the sun descending
Know that they are always near
And their vigil never ending
And they face the things we fear

For they are our good protectors
They are strong, and kind, and brave
While the Lance does still protect us
Little children can sleep safe

- Crystal Empire nursery rhyme, author unknown

After a thousand years of absence, the Crystal Empire has been freed from Sombra's curse and returned to the world. The crystal ponies can finally live free from fear and slavery, but their once mighty nation has dwindled to a mere shadow of its former glory. Still, their tribe was never known for a lack of tenacity, and with their chains broken at long last, the crystal ponies are willing to face any challenges the world might throw at them.

I these difficult times, the young crystal pony Ruby Chip has risen to knighthood, and proven herself to be worthy of joining the legendary Order of the Crystal Lance. It seems like she has achieved everything she ever dreamed of, but then she starts being plagued by dark and frightening visions from the Empire's troubled past.
To make matters worse, Ruby fears that the Order might come into conflict with the Empire's new ruler. As a former officer of Equestria's military, Prince Shining Armor is not very fond of the way the Empire's armies are run and organized, and sees them in dire need of modernization. It remains to be seen if the traditional warrior caste of the Empire still has a place in the military force he seeks to create.

Very soon, Ruby and her brothers and sisters in arms will have to prove that they are more than a misplaced remnant of a long gone era, and show that the knights of the Empire can still fulfill their sworn duty as champions and protectors.

However, whether or not Ruby herself will be ready to be the pony others need her to be, that is another question altogether.