Princess Cadance needs our help, her magic will not last forever. I think we can do it, but we need to work together. We have to get this right, yes we have to make them see. We can save the Crystal Ponies with their history!
Written by Meghan McCarthy
Princess Celestia is sitting in her throne room when a guard runs into the room. He announces that news has arrived from northern Equestria: "it" has returned, and Celestia, wanting to take immediate action, sends her guards to find Princess Cadance and Shining Armor before writing a letter for Twilight Sparkle to come to Canterlot immediately. In Ponyville, Twilight Sparkle is scurrying around her room looking for quills, books, parchment, and supplies, all the while panicking at the prospect that Princess Celestia has told her that she will be taking a test. In Canterlot, Luna and Celestia discuss Twilight's preparedness for the mission, but are interrupted by Twilight's arrival. Twilight discovers that her supplies are unnecessary, as her test will be a different sort—Princess Celestia explains that the Crystal Empire, a long-forgotten civilization, has returned after a thousand-year absence.According to Princess Celestia, the Crystal Empire was ruled by King Sombra, an evil unicorn whose heart was black as night. Because the Crystal Empire reflects the nature of the ruler across all of Equestria—bringing light and happiness if the ruler is benevolent and darkness and sorrow if the ruler is a tyrant—the Princesses transformed Sombra into a shadowy cloud and banished him to the arctic wastes, but not before he cursed the Crystal Empire to disappear along with him. Celestia tasks Twilight and her friends with aiding Shining Armor and Princess Cadance in finding a way to prevent the Crystal Empire from falling back into Sombra's hooves. Celestia reassures her student that she will succeed, and will proceed to the next level of her studies upon her return. As she leaves, Celestia tells her that she, and she alone, must be the one to help Cadance and Shining Armor do what needs to be done.Twilight, Spike, and the rest of the Mane 6 travel to the Frozen North and are greeted by Shining Armor, who urges them to follow him quickly, as the Empire "isn't the only thing that's returned." As they cross the tundra, Shining Armor informs them that King Sombra has been attempting to invade the Empire. Twilight questions what point there is in finding a way to protect the Empire if it's already being protected when King Sombra, in the form of a shadowy mass, attacks and chases them. Shining Armor stays behind to hold King Sombra off while the others reach the Empire. He escapes but Sombra curses his horn, preventing him from using his magic.The Mane 6 meet Princess Cadance, who is using her own magic to form a protective shield around the Empire that is keeping King Sombra out. However, she has grown weak due to the constant concentration required to keep it active. Twilight comes up with the idea to interview the Crystal Ponies, and the Mane 6 set out to find a way to restore the Crystal Empire to the way it had been. They find that the residents—in a rather dull coloration for a bright kingdom—can't remember anything before King Sombra came to power, and don't want to remember anything about his reign. They head to a nearby library to look for information, and Twilight finds a book with information on the Crystal Fair, a festival that will unite the hearts of the Crystal Ponies. Central to this fair is something called the Crystal Heart, but as they do not have one, Twilight cuts one out of a crystal block to use as a substitute.Twilight summons the Crystal Ponies to the fair, and as they begin to enjoy themselves, their previously dull coloration begins to brighten, as does their mood, and they begin to remember their previous lives. However, Rainbow Dash overhears a remark that the Crystal Heart is in fact an artifact that the Crystal Ponies power with their love and unity, and that King Sombra hid the Crystal Heart where it would never be found. Rainbow Dash rushes to cover up the fake heart and tells Twilight about the problem. Twilight Sparkle finds the last page in the book had been removed by King Sombra to preempt any attempts at discovering the Heart's significance. Princess Cadance suddenly faints and the magic shield surrounding the Crystal Empire vanishes. King Sombra, seeing his chance, advances into the kingdom...TO BE CONTINUED*Cue happy credits music*
King Sombra was "turned to shadow" and banished to the ice of the arctic north. Whether that entails this is unclear as of yet.
The Crystal Ponies were kept as Sombra's Slave Race, and have spent the last thousand years after his defeat with no contact with the outside world and stuck in a state of despair and unhappiness. Worsening it is the fact that they have no memory of the time before that, meaning all they could remember during that time was being his slaves. It's mitigated a little by the fact that the Crystal Ponies are under the impression that they were part of Equestria "yesterday", implying that they didn't live out the thousand years they had disappeared for, but simply skipped forward in time.
Princess Cadance copies Shining Armor from the wedding by projecting a protective field of love around the Crystal Empire to keep King Sombra at bay. Unlike Shining, she must maintain the spell constantly, resulting in sleep-deprivation.
The point of the Crystal Heart was to avert this trope; every crystal pony in the empire contributes to charging it up so no one person has sole responsibility for the empire's protection.
Beauty Is Never Tarnished: Averted once again for Cadance. After days without sleep she has bags under her eyes and droops with fatigue. Just as before, this also serves as straight Unkempt Beauty.
Big Bad: King Sombra is the latest threat to Equestria and he's starting with a campaign to retake the Crystal Empire.
When the mane six ask if there are any books on the history of the Crystal Empire, the librarian responds that she doesn't know, because she can't remember. She doesn't even know if she actually works in the library at all. A few scenes later, when she regains her coloration, she happily shouts "I DO work at the library!"
Pinkie's friends quickly learn she does not play the flugelhorn well. Later, Rainbow Dash outright ignores Pinkie's desire for a flugelhorn when handing them out at the crystal fair.
Burning with Anger: When Spike (after donning protective gear) tells a tense Twilight she's overreacting, we cut to a shot of Ponyville, where a charred version of Golden Oak Library momentarily launches into the air before falling back down.
In "A Canterlot Wedding", Shining Armor had to keep up a massive shield over Canterlot with Cadance supporting him. Here, it's reversed. Princess Cadance is the one who has to power the shield to protect the Crystal Empire with Shining Armor supporting her.
The Dark Times: King Sombra ruled the Crystal Empire with an iron hoof, relegating its populace into slavery. Even after being freed, the once cheerful Crystal Ponies are still miserable and shudder in fear at the memory of Sombra's rule.
Data Crystal: Celestia keeps a crystal that stores a hologram of her and Luna deposing King Sombra.
Downer Ending: Par for the two parters. It turns out Twilight was wrong and they needed to find the Crystal Heart instead of making one, resulting in Cadance's power running out. King Sombra's shadow form washes over the Crystal Empire as the field fails.
The Dreaded: If the reaction of the Crystal Pony that Twilight speaks to is any indication, King Sombra is this for the Crystal Ponies. The way that Celestia talks about him implies this is far from unwarranted. Shining Armor also displays fear when speaking of him.
Dull Coats of Unhappiness: The crystal ponies have washed out color schemes to go with their depressed voices. Even when they're happier at the prospect and events of the Crystal Fair, their coats don't gain the incredible sparkling lustre they should have, instead simply looking like regular (though still fancy) Earth Ponies.
Eternal English: Despite having been gone for a thousand years, the crystal ponies speak modern English, which can't be said for Princess Luna.
The Exile: King Sombra was turned into shadow and sealed in an icy crevice by Princesses Celestia and Luna for the enslaving of the ponies of the Crystal Empire. Returning from his banishment starts the plot.
Face Hoof: Rainbow Dash does this after a Crystal Pony she's interrogating tells her she doesn't remember anything about King Sombra's rule.
Face Plant: Pinkie Pie slams face-first into a pole when playing with her night-vision goggles.
Failed a Spot Check: Twilight, the book fanatic, missed the fact that the last page of the book was torn out!
Fisher King: Under the rule of King Sombra, the Crystal Empire became Mordor. In this case, Sombra is shown corrupting the land with his evil magic.
Fish Out of Temporal Water: The Crystal Ponies are unaware that the Crystal Empire has been gone for a thousand years. When they're told, they understandably have a hard time believing it.
Celestia tells Luna that if Twilight succeeds in saving the Crystal Empire they will know she is that much closer to being ready for something, but doesn't say what.
Cadance's cutie mark, first seen several months before this episode aired, incorporates the Crystal Heart, implying that she was always destined to rule the Empire.
Forgot About Her Powers: Twilight seemingly forgets that she can teleport while running from King Sombra. Given the large group with her, it's possible she couldn't teleport them all; indeed herself and three people was such a struggle back in "Dragon Quest" that she failed on her first attempt. It could also be she wasn't familiar with the area; teleporting into a wall or one of those crystal spikes wouldn't end well.
Funny Background Event: Pinkie Pie after removing her "Fluttershy" disguise leaves it there on the ground. As the other ponies talk, Fluttershy walks to the rest of the group and reacts appropriately to seeing what looks like her skin on the ground.
Generic Doomsday Villain: King Sombra is built up as being a huge threat to the Crystal Empire, and is also revealed to have set up an intricate security system to prevent anypony from getting the Crystal Heart in the past, but other than that, his characterization is nonexistent, especially in comparison to the show's other villains, and there is barely any backstory for him to speak of. This isn't helped by him speaking very little and not having any meaningful interaction with the other characters and spends most of the two-parter as more of a wave of blackness rather than an actual character. The show treating him more like a powerful malevolent force than a character in his own right. According to Word of God, he was intended to be more of a menacing and terrifying presence lurking over everything. In other words, fear itself.
Happily Married: Cadance's lyrics from Canterlot Wedding part 2 include "love and cherish him each day". We see her and Shinning Armor engaged in precisely that; their marriage is literally the only thing that's keeping the Crystal Empire from collapsing.
I Remember It Like It Was Yesterday: One of the Crystal ponies says this regarding Sombra's reign, though it's not a set-up for a flashback. It seems to suggest that the curse transported the Crystal Empire 1000 years forward in time.
Late-Arrival Spoiler: Inverted. The Target-exclusive toy sets spoiled some things about this arc before any clips from the episodes were released!
Merchandise-Driven: Toys from this line are scheduled for 2013, and some Target-exclusive sets have already been released in physical stores. King Sombra is a normal unicorn (when he's not a smoke monster) which is presumably much easier for Hasbro to manufacture than (say) Discord.
Mineral MacGuffin: The crystals of the Crystal Empire are affected by emotions. Filling them with love causes them to emit love. Filling them with negative emotions causes them to turn dark and start infecting everything in contact with them.
Mood Whiplash: As usual, the cliffhanger of this episode is immediately followed by the happy credits music.
Celestia when her scout informs her that Sombra has returned. She instantly goes into "avert-the-crisis" mode.
When the Mane Six learn that the Crystal Heart is a specific item and thus they are just as vulnerable to Sombra as ever.
Orcus on His Throne: After sealing Shining Armor's magic, King Sombra spends the rest of the episode waiting for Cadance to tire without doing anything to hurry the process along. Justified as contact with the shield seem to be physically painful for him. It is shown to be able to cut through his horn at the very start of Part 2.
Power Crystal: The Crystal Heart projects a barrier to keep the Crystal Empire safe and it is refueled by all the ponies in the Crystal Empire.
Black Spy Catsuit with a balaclava? Check. Stealthy rooftop skipping? Check. Rappelling into the scene? Check. Three-lensed Night-Vision Goggles? Triple check. Pinkie has apparently been taking lessons from Sam Fisher.
Unreliable Illustrator: What is supposedly a crystal flugelhorn looks more like an instrument out of a Seussian fantasy land than any actual flugelhorn. (Real flugelhorns don't have two bells, for one thing.)
You Shall Not Pass: While running from King Sombra, Shining Armor remains behind to hold him off so the Mane Six and Spike can reach the Crystal Empire safely. He survives but his horn is corrupted and so he is unable to cast his defensive spell to help Cadance.