Ever since she was a small filly, Twilight had always enjoyed the sound of trains, as well as the way they moved along the tracks. She had not travelled on them much prior to her move to Ponyville, but on the few times she would venture on one with her parents, it was always a pleasant experience. She tried desperately now to focus on those happy memories, as a way of distracting herself, calming herself. But not matter how much she tried to, the grim truth of reality always broke through.

She opened her eyes, having had them closed previously to try and focus on the train sounds, and looked around her cabin. Her friends were all there, sitting in their respective seats, as was Trixie. All of them had the same look of worry and concern. Despite Rainbow's speech prior to their departure, it was clear that it had done little to alleviate their fears. Even Pinkie, who was usually so upbeat regardless of the situation, was looking uncharacteristically down.

Twilight sighed, secretly loathing her decision to bring them here. They were all important to her and the last thing she wanted was to put them in danger. But she knew she had little choice in the matter. Turning from them, she looked out of the window. The rain was now travelling along a stretch of mountain range, one that Twilight knew well. It wouldn't be long before they stopped in Canterlot. From there the plan was clear. Wait for Sombra to arrive and see what they could do to stop him.

She focused on that. They had a weapon to use against him. And although she did not know if it would work, she knew that it was their only hope. But she was jarred from her thoughts but a sudden jolt. The train was stopping almost immediately, shocking everypony on-board and causing the entire group to leap out of their seats in surprise. The screech from the train's wheels braking was almost deafening. The group all looked at each other with confusion and concern.

"What in tarnation was that?" Applejack asked.

Twilight had no answer, but she didn't need to, because the door of their cabin opened and a stallion in a blue uniform, no doubt one of the train operator, entered, looking very nervous.

"Mares and gentlecolts! May I please have your attention! Due to unforeseen circumstances, the train has had to come to a stop. We apologize for the delay!" He said.

Twilight, concerned that her plan was now in jeopardy, ran towards him and brought her face up close to his.

"What do you mean, unforeseen circumstances?" She asked angrily.

The stallion took a nervous step backwards as he hastily tried to explain himself.

"We....we don't know! There's some.....thing blocking the train! Keeping us from Canterlot! I don't know more than that!"

Twilight said nothing in response. Instead, she looked over to the window she was sitting next to a few moments ago. Curious as to what was happening, she ran over to it, opened the window and poked her head outside the train. Looking ahead, she understood immediately why the train had stopped.

Because there was Canterlot right ahead of them. But the train had stopped just short of a glowing yellow mass of magic. Twilight had seen such magic once before. It was a barrier spell. She'd seen her brother, Shining Armour, cast such a spell over the city not too long ago. Looking up, she saw that the field encompassed the entire city, just as Shining's had once done. And the colour of the magic made it clear who was casting it. She'd seen that magic plenty of times to know that it was Celestia who was behind this.

Pulling her head back into the cabin, Twilight turned and saw her friends and Trixie gathered around, no doubt waiting for an explanation. So Twilight gave it to them.

"It's a magical shield. I think Princess Celestia is preparing for Sombra's attack." She said.

The group gave each other looks of concern before Rainbow spoke up.

"How? The last time one of those shield was up, the train was able to move through just fine."

Twilight nodded.

"Yes. But Shining Armour didn't have the spell on at full strength. It was only partially powered to let ponies and the train through. If the enemy threatening Canterlot had arrived, he could have used his full power at a moments notice." She explained.

Rainbow seemed frustrated at this answer, as evidence by her tone when she spoke again.

"So what do we do? Can we get past it?" She asked.

Twilight considered this for a moment before answering.

"I'm not sure. I've never tried breaking through a shield spell before. But I suppose we could try."

The group nodded in agreement at that and all turned in unison and began walking towards the door leading outside of the cabin. They opened it and leapt out. Once outside, the group began running along the train tracks until they reached the front of it, mere feet away from the barrier. Twilight approached. closer than the others. Gently, she placed a hoof on the barrier. It felt warm to the touch. She knew it wouldn't harm her unless she really tried to force her way in.

Looking back at her friends, she saw them all give her reassuring smiles. Twilight nodded at them before turning her attention back to the barrier. She closed her eyes and concentrated, causing her horn to glow. She aimed a beam of magic straight at the barrier, but it just soaked it up like a sponge. Frustrated, Twilight tried ramming her magic-infused horn right into it, but that did little better. Frowning, Twilight tried to think of some other way that they could get through. But her thoughts were interrupted by the feeling of a hoof on her shoulder. Turning, she saw Fluttershy, looking very scared about something.

"Twilight......what's THAT?!"

Twilight saw her point to something and turned to se what she was looking at, as did the rest of the group. They saw, far away in the sky, what looked like a dark cloud of some sort. Twilight stepped forward and squinted her eyes, trying to get a better look at it. The cloud appeared to be getting bigger, but it was not long before she realised that it was, in fact, getting closer. Her eyes widened with horror as the cloud became more clear to her.

For it was not a cloud at all, but the changeling swarm. Hundreds of drones, all flying in unison, soaring through the air and towards the city. It would not be long before they reached the shield. Looking at her friends, Twilight was at a loss for words. She didn't know how to get into the city with this shield up. So she instead turned back to the sight of the swarm, which for the time being didn't seem to notice them. It was here that Twilight noticed something flying ahead of the swarm. Something that looked like a much smaller, and blacker, cloud.

Her eyes widened further as a cold feeling grew within her heart. She knew that darkness anywhere.

"It's.........him!"

.....................................

It had been many centuries since he last felt excitement such as this. Sombra, though he lacked the wings of an alicorn or pegasus, was held aloft in the sky by the sheer force of his dark magic. And he had plenty to spare for what was coming. He looked down from his high place, surrounded by his changeling followers, at the glittering white city below. Canterlot, they called it. A city that did not even exist a thousand years ago, when he was first imprisoned.

A city that rivalled even the glittering palace of the northern Crystal Empire, which he himself had once conquered. And now, as before, he would conquer again. He felt the same rush as he did back then. Waves of his enemies would throw themselves at him in a desperate attempt to thwart his plan. And like centuries ago, they would fall to him. True, this time his target may have had the protection of two alicorns, something the Empire never had, but this time he too had upped his game, with an army.

As he gazed upon the city, he broke into a wide grin.

"Such a beautiful city. A thousand years it must have taken to forge a place such as that. And in just one day, I will crush it."

Sombra looked through the corner of his eye to see his lieutenant, Lightning Dust, flying alongside him. He didn't need to look at her completely to know that she was clearly nervous about the upcoming fight. He wondered silently if she had the stomach for it. Regardless, it didn't matter right now, because first he had to get past the city's first line of defence. A massive bubble, created from powerful magic. Sombra knew that magic anywhere, and chuckled at the sight of it.

"Nice try mother. But it will take more than a simple shield to stop me."

With that, he turned around to the changeling horde behind him. The sound of all their wings buzzing was near deafening, but he ignored it. If he knew one thing, it was fear. And he knew that these changelings were afraid, and with good reason. The last time they were here, they were defeated. And so, being their current commander, Sombra decided that the time was right for a little motivational speech, as cliché as that might have seemed to him.

"Changelings! Before you stands the capital city of Equestria! Many of you know it, for this is not the first time your eyes have beheld it. When last you laid siege to this place, you were defeated. You were broken. You were cast out and humiliated. But today! Today, it is the PONIES who will know the sour taste of defeat! Follow me on this day, and we will show Equestria what true power looks like!"

That did it. The changelings snarled with approval, a sound almost as loud as their buzzing. Sombra, having frequently worked alone, would have preferred to just get on with the attack, but he knew the value of a little push here and there. But now was the moment of truth. Closing his eyes, he concentrated on his magic. The jewel on his alicorn amulet began to glow a bright red, as did his horn. Opening his eyes again, they too were glowing. His magic was building higher and higher, to the point where the changelings surrounding him began to back away in fear of him.

Eventually, his magic had built to sufficient strength, and he pointed his horn directly towards the shield surrounding Canterlot. With a look of almost joy, Sombra fired. The magical blast from his horn was larger and more powerful than any magic seen by the changelings, or Lightning. No doubt given additional strength by the amulet, it streamed down through the air and approached the shield at tremendous speed. In mere moments, it collided.

The impact of the blast upon the shield sent shockwaves through the air, to the degree that many changeling had to flap their wings even harder so as to not get blown away. The blast continued to pummel against the shield, with Sombra growing more and more angry the longer it took. Eventually though, cracks began to appear in the area that was being attacked. With his smile back once more, Sombra pushed even further with his magic and the blast made it's final efforts.

With the full power having been brought down upon it, the shield broke. It's cracks spread all over and it shattered like glass, with it's pieces disappearing as they fell. The city was now exposed. Their first line of defence brought down without so much as a sweat on Sombra's part. The day was going well it seemed. Turning back to his changeling army, he looked at their faces, at the looks of utter glee and anticipation. They were eager for battle. Hungry for it. Turing back to the city, he pointed towards it with his hoof and gave the command.

"Changelings...........ATTACK!!!"