The Crystal Empire was a beautiful sight at night. The aurora emanating from the crystal heart danced in the sky above, lending a soft light to the city below. The spire of the royal palace towered over the other buildings and glimmered in the magical light. The city, while bustling with activity in the day, slipped into a quiet peace at night. A few ponies were still coming and going and the guard stood ever vigilant, but most of the citizens were tucking in for a good night's rest. The last train of the day pulled into the central station and, as always, the station attendants moved to open the doors and let out the what few travelers were expected. The head attendant noted that the train was a few minutes late, which was odd as the Equestria railroad was famous for always being on time, the expected result when all the employees had cutie marks that were schedule and transportation related. Also the lights inside the train were all dark and the windows all had their curtains drawn.
"Was the train empty?," the attendant wondered. Even then the crew usually kept some lamps lit so they could see. All Tartarus broke loose the instant the first door opened. A tidal wave of black ooze and smoke cascaded out the doors and exploded out the windows, instantly washing over all nearby ponies. Tendrils of dark energy and shadow shot out of every crevice on the train and seized shocked bystanders. The panicking ponies couldn't even process what was happening and ran screaming in random directions. Gloom calmly stepped off the train, leaving behind the gibbering wrecks that were the crew and passengers. Gloom stood on the platform and reached out with both his mind and magic, feeding the wave of negative energy that he had built inside the train during his short trip. The wave continued to spread across the empire, although slower than his influence had spread in Canterlot and Ponyville. The aura of the crystal heart pushed against his power, slowing it. The guard had begun to react, and alarm bells sounded across the city. It didn't matter, Gloom's onslaught spread faster and faster as it gained momentum from the misery of the ponies already overcome. Gloom learned from his first few victims that it was easy to break these ponies, all he actually had to do was force an image of Sombra into their minds and they folded like a house of cards. The evil king must have really traumatized them to still affect them so. Gloom had analyzed the memories he took from the passengers and noted that Sombra had used a very basic version of Gloom's own magic. Sombra had learned to enhance his powers with his own hatred and the fears of other ponies and there were implications that he was trying to corrupt the crystal heart to do the same, although he never succeeded.
"What an idiot," Gloom thought, if he had only moved beyond such limitations no power save harmony itself could have beaten him. Hate and fear were powerful, but they were only 2 aspects of misery, to achieve real power one needed to include pain, rage, doubt, and most importantly, despair. Gloom had learned a long time ago, in his "youth" (if that's what it could be called), that a single emotion, no matter how strong, could be easily overcome by nasty things like love and friendship. Gloom shuddered as he thought of his past encounters with positive magic. Horrible lies meant to deny and sugarcoat the true nature of this world, but he had no choice but to acknowledge the power of "good" magic, after all, lies could be strong. Gloom wondered if the crystal heart could be corrupted, if not it would be a shame to have to destroy such a powerful artifact.
Shining Armor awoke to alarm bells, his wife Cadance sitting bolt upright beside him. The two royals sprang out of bed and rushed to the nearby balcony door, throwing it open in the process. What they saw shocked an horrified them, a huge black cloud washing over the southern quarter of the city. Ponies screamed as they ran from the cloud of doom and some of the guard desperately tried to guide the evacuation. Behind the couple, a team of guards threw open the door of their chambers. A captain quickly ran to their side, "Prince! Princess! The empire is under attack! That cloud has overtaken an entire district and is coming this way fast! What do we do?!"
"What is that? Where is it coming from?" Shining demanded
"Is it Sombra? Is he back?" Cadance asked.
"We have no idea. It came so fast, some of my guards say it started at the train station and they saw some sort of monster leave the train," the captain responded.
"Get everypony out of that cloud's way and to safety. Once all the civilians are safe spread the word that the crystal heart needs to be powered up." Shining ordered. The guards ran to carry out the command.
"Shining, add your magic to mine. If this really is dark magic, then maybe we can push it back with a powerful protection spell like with the changelings. At least we might be able to buy time for our citizens to power up the heart," Cadance said.
"Good idea, ready when you are!" Shining replied. The unicorn and alicorn closed their eyes in concentration and slowly approached each other, their horns glowing brightly. When they were within hoofs reach, they lowered their heads and the very tips of their horns touched. A bright pink light lit up the room and a ball of magic began to build from where their horns touched. Their eyes remained closed as the spell took form. Shining formulated the details of the spell, making it only affect dark magic, leaving innocent ponies and buildings unharmed. It also needed to expand outward instantly in all directions with force so as to push away any enemies and stop at the border of the empire so as not to drain too much of his and his wife's energy. It was a complicated spell, but Shining's talent was protecting others and he had mastered spells of this kind. Cadance provided most of the power, drawing upon the incredible reserves of strength alicorns possess as well as her unique ability to utilize her love for Shining and for her subjects. The result was one of the most powerful works of magic ever seen in Equestria, a power great enough to repel an army of changelings and a queen with power exceeding Celestia's. The royal couple's eyes opened in unison, glowing bright pink, and the the spell exploded outwards.
Gloom casually walked on all fours through the streets, just behind his wave of shadow. He could sense the ponies running from his magic. It was futile, the other part of his wave was slowly encircling the empire and there was no way more than a handful of ponies would be able to escape before they were surrounded. Suddenly, he heard an explosion from the palace. For a moment, Gloom feared that the ponies had somehow gathered together and coordinated enough to power up the heart, but then he saw that the bubble roaring towards him was pink, not the characteristic white of the heart. A simple protection spell? Gloom simply charged his cloud with enough energy to overcome a dozen unicorns and waited for the bubble to shatter itself on his power. To his surprise and shock, the bubble didn't even slow down as it blew right through his cloud and threw all of his darkness back. He could never outrun it and there was no time to perform a teleport spell strong enough to take him outside the city, so he dug his claws into the ground and lowered his head like a bull. At the same time he channeled as much of the black liquid that flowed through his body as he could to the top of his skull and solidified it, forming a kind of helmet. He added a short, but sharp, horn for a chance to pierce the bubble. He also sent some of his mass to his legs and claws for a more secure grip. Gloom was a master of his own body and although he could not shape-shift like a changeling, he could quickly change between solid, liquid, and gas as well as reconfigure his mass. Being made of magic liquid has its advantages. A second after he finished, the spell struck him head on.
His horn crumpled and his skull cracked under the massive force. It was like being hit by a train. His front legs were torn from the ground, taking chunks of it with them; his hind legs still held, but he was pushed back several feet, leaving two small ruts in the street. He threw himself forward, slamming his claws into the bubble and trying to physically push it back. The bubble started to slow, then stopped about half a block back from where it collided with him. Gloom roared as he strained against the spell, putting the entirety of his physical and magical strength against it, even drawing some power from his other two bodies. The Ponyville one had some to spare, but the Canterlot one could only give a little as it had just engaged Celestia. He also commanded what remained of his cloud to push inward. He felt the magic behind the bubble and recognized it instantly, somehow somepony knew love magic.
Back at the palace, the royal couple knew something was wrong. Their spell had been working fine, the cloud had retreated, but something had caught their attack and was pushing back. "CMON!! GO!!!" Shining Armor yelled at nothing as he strained to maintain the spell, pouring all his magic into it.
"NO! Don't give out on us now!" Cadence said as sweat began to drip down her face.
"LOVE WILL NOT SAVE YOU PONIES! IN THE END IT IS JUST ANOTHER SOURCE OF PAIN!" Gloom's voice echoed across the empire in a way that rivaled the royal Canterlot voice, reaching the ears of the royal couple.
"What in Tartarus was that?!"
"Shining! I can't hold it!"
Cracks started to appear in the bubble around Gloom's claws and with a final snarl, Gloom threw the last of his might against it and it caved in. Gloom fell forward as the bubble shattered in front of him like glass, the break spreading upward and around until the entire dome disintegrated. Shining and Cadance collapsed, their strength completely exhausted and their magic expended. Gloom's cloud of darkness rushed into the empire, claiming more helpless ponies for Gloom to feed from. Gloom lay on the ground for a few minutes, unable to get up, but soon his power began to return as new negative energy flowed into him from fresh victims in addition to the constant stream he received from old victims. His broken body repaired itself and he restructured it back to his default look. To his horror, another light sprang up from the center of the city, the ponies that had outrun his cloud had gathered beneath the spire, and were powering up the heart. Only about a third of the population had made it there, but that was still enough to be a threat if they channeled their love through the heart. Gloom focused on his cloud and commanded it to channel into a stream for increased speed, but less coverage. He didn't need to cover ponies he already owned, although it did strengthen his hold on them. The river of shadow rushed into the central square just as the ponies touched their muzzles to ground in unison. A wave of blue energy rushed to the heart and the crystal began to spin, but as Gloom's attack overtook the ponies, the blue light dimmed and spinning slowed. There was no longer enough happiness in the empire to power the heart and despite valiant efforts from the ever dwindling resistance, the heart's light flickered and dimmed. In minutes, every last crystal pony had fallen to Gloom's influence. Gloom calmly walked through the square as his cloud expanded through the palace and covered the entire city. The sound of thousands of crying and wailing ponies was like music to his ears as he approached the dimly glowing crystal heart.