Celestial inhaled sharply as she felt another wave of attacks pummel her barrier. The growing and near constant barrage was beginning to wear on her, not to mention sustaining a barrier of such a size. Just then Luna teleported in, looking absolutely exhausted.

“I… I don’t think… there are any… anymore ponies… outside,” she gasped.

Celestia winced. The amount of ponies she had felt enter her barrier was… not promising.

“Discord-” she began, about to turn and ask him advice, but stopped when she saw him holding his hands in front of him, concentrating deeply. There were a few sparks of red, erupting into a hellish flame for a moment, before it quickly fizzled out. Discord exhaled, the act having obviously caused him some exhaustion. “... What was that?”

“Huh? Oh, sorry. Trying to figure out just how much of my chaos magic I can tap into right now,” he answered. “It’s not much, but… well, the right tool at the right time can make all the difference.”

“I… see…” she answered. “Do you have any suggestions for the moment?”

“Would you be able to hold that shield better if you shrunk it?”

“I… suppose so. I don’t feel comfortable letting them get closer though.”

“Give some ground to gain some time, or lose both at once? Seems like an easy choice to me.”

Celestia sighed and nodded. “Luna, could you call the guards by the edge of the barrier to come back in?” she asked.

Luna nodded. “Of course, sister,” she replied and galloped off.

“Discord, is your ‘specialist’ truly going to be enough?” Celestia asked.

“Tia, trust me. Once he gets here, all our problems will be over. I’m sure he’s doing everything he can to get here as quickly as possible,” he assured her.

The unicorn guard Stalwart stood at attention by the door to the next car, making sure to keep his eyes trained on the strange armored creature sitting in one of the seats. He had been informed of the creature having teleported aboard, which was usually the sign of somepony trying to sneak on and avoid paying for a ride, but it had had a ticket. The real problem was the terrifying aura it exuded, so intensely and obviously that everypony had done everything they could to get away from him. Unfortunately, with this being a fully booked train, even everypony trying to squeeze in five or six to a seat didn’t provide enough room for everyone and one poor soul was seated next to him. The stallion nervously cast glances at the creature which crossed its arms and appeared to be rather annoyed, judging from its body language.

“So, uh… not from around these parts I take it?” the stallion asked nervously. The creature didn’t respond. “I’m from Baltimare myself. First time visiting Canterlot. You, uh, look like you’re from a lot farther away than that.”

What is that fool doing? Stalwart thought, afraid that this harmless banter could quickly escalate into violence. He gripped his spear tighter, ready to use it a moment’s notice.

“I’m just going there to check the place myself. You know, the Royal Palace is one of those things you’ve just got to see with your own eyes once, am I right?” he smiled nervously. The creature made no response. “I’m… I’m sorry, I’m just… trying to clear the air a bit,” he trailed off as he hung his head.

The creature turned its head to cast a glance at him before audibly sighing. Stalwart tensed when the creature unfolded its arms and reached over to the stallion, only to pat his head like he was an annoying dog who was begging for attention. It then quickly folded its arms and continued to look straight ahead.

The stallion looked surprised for a moment, before smiling. He turned to keep talking to the creature only to stop as his eyes looked towards the window. “Hey buddy, ever see one of those before?” he asked nervously.

The creature visibly moved its head in an eye rolling motion before turning to face the window. The next moment it shot up from its seat, pulled a large pronged-like device glowing with blue light from nowhere, and aimed it at the window. After barely a second of it emitting humming noise that quickly rose in pitch it fired a blue beam of energy that shattered the window, causing the other passengers to scream in shock and terror.

Stalwart immediately readied his spear and charged, watching as the creature somehow dispersed his weapon and retrieved another one, this one lacking any glowing parts and being large enough that he had to have it resting on his shoulder. He aimed it out the window for about a second before it loosed three objects that resembled fireworks in quick succession. Stalwart cast a quick glance at their trajectory before turning back, only to freeze as he looked again and saw what the projectiles were headed for. He only caught a glimpse of it but it looked like a red ball of flesh, as large as a chariot, with one malevolent eye, a some horns, and a giant maw with more teeth than he dared count. It was blasted apart as the three projectiles exploded as they made contact with it.

Another scream came from behind him, and he turned to see three creatures, all of them looking like monstrous goat skulls with glowing red eyes and cloaked in flames, screeching like beasts as they charged the train. Before he could properly react the armored creature dashed past him, now holding what looked like a miniature cannon with two barrels. It fired with a deep “Boom” and shattered the window with a spray of metal, hitting one of the monsters and causing it to explode. It repeated this on the second, and on the third it quickly pulled out another weapon, this one unleashing a quick volley of metal that caused the final skull monster to explode.

Before Stalwart could gain his bearings an explosion and screams of terror and pain came from the car next to them. Looking outside, he saw more of the balls of flesh with mouths and the flaming skulls approaching from the distance, in addition to newer ones with pale skin and crown-like horns around their heads, closing in and ready to swarm the train. He turned back to the armored creature who quickly pulled off part of the weapon his was carrying, stashing it away somewhere, and then pulling out a lens that he affixed to the top of it. He then somehow dispersed it, only to pull out an even bigger weapon with several barrels arranged in a circle in front of it. He quickly removed the barrels with the more angular design and replaced them with a more rounded one. Finally, the creature summoned three symbols, hovering in front of him as if they were made of flames, and that Stalwart felt an incredible amount of evil magic from. He quickly swiped away one before replacing it with another, and then dispersed them all. This all transpired in less than thirty seconds and then, without a word, the creature hefted his large weapon, the barrels spinning on their own, before rushing towards the other passenger car and kicking the door open.

After taking a moment to recover, and being shaken from his stupor by the sounds of battle coming from the next car, Stalwart chased after the creature. What he found in the next car could only be described as a war zone. Dead ponies were strewn along the floor, some in pieces, while others were injured and trying to get their bearings, and still more were cowering in fear. Seats and walls were on fire, and a massive hole was in the left side of the car, large enough that even some of the axles and framework of the wheels was visible through the floor. The creature was firing his weapon out the window, the barrels spinning and spewing out projectiles at a rate that would put an entire battalion of crossbow ponies to shame, practically mulching the flaming skulls and fleshy orbs that were attempting to attack from outside.

Suddenly one of the thin and pale monsters flew in crackled with red energy. A moment later a hulking brute of a beast with no eyes appeared from the pool of energy. The armored creature fired at it, the projectiles easily passing through it and hitting the pale creature as well, blasting it to pieces. While it did this, the hulking beast leapt into the air, its hands glowing with power, before bringing them down. The creature jumped out towards the hole in the car while continuing to fire, the hulking beast slamming its hands on the floor causing an explosion of power. Instead of simply flying out of the train, the creature somehow curved its trajectory in mid air, a short burst of fire coming from its feet, before landing back in the car on the other side, firing at the beast all the while. The hulking beast fell to its knees and then the creature jumped onto its back, slamming its head to the floor, before pulling it back up and then ripping its jaw off. A moment later, some blue energy flowed from the beast to its killer.

Stalwart just stared at the creature, unable to believe what he’d just seen.

No, not “creature.” Those movements were too well practiced. And those weapons… this is a soldier.

The still living passengers stared at him with both fear and awe, and the soldier turned to go to the next car.

“W-Wait!” Stalwart called, the soldier turning back to face him. “... Please, send any ponies you come across to the front of the train. We’ll protect the engine and make sure it doesn’t stop.”

The soldier just stared for a few moments before grunting in understanding, turning to face the door as he spun the barrels of his weapon before dashing forwards and smashing through it.

“Stalwart, sir!” called some other guards as they approached from behind.

“Emergency situation!” he barked as he turned to face the other guards. “I need the unicorns to the front car, the rest help the wounded and herd all the passengers to the front car! We can cast a barrier spell that can protect both them and the engine if we combine our magic.”

“What about the monsters?” one of them asked.

Stalwart turned to face the opposite door. “Somepony else is going to handle that.”

Well what do you know? They’re not all pussies after all, the Doom Slayer thought as he removed his fist from a Cacodemon’s eye socket, using his thrust boots to make it back to the train car. He was a bit annoyed at having to switch out his Armored Offensive rune for In-Flight Mobility, but it was more suited to this situation. Besides, Seek and Destroy still allowed him a great reach when finishing foes off, and so long as he made sure to take stock of his surroundings he wouldn’t have to worry about Rich Get Richer deactivating.

He spooled up the chaingun as he prepared to kick down the door to the next car, ignoring the ponies cowering under and behind the seats. He had already seen others make a break to the front as he went past them, so any of them who didn’t move had no excuse. He kicked the door down and entered the next car, immediately noticing the Summoner on the left side preparing a wave of hell energy and opened fire, the bullets easily punching through both the walls of the train and the Summoner’s flesh, stunning it. It took a few seconds of well aimed lead spray, but it went down quickly enough. A Cacodemon came from the right, and he swung his weapon to aim at it, not even bothering to let go of the trigger as he did. Just like the Summoner, it was quickly mulched as well. He let go of the trigger while keeping the chaingun spinning as he raced towards the next door, only to hear the unmistakable screech of a Lost Soul from behind. He turned and unloaded on it, destroying it almost instantly, repeating this with the next three that came afterwards, and quickly kicked the door to the next car open.

The moment he did he heard something land on the roof of the car. Without a second thought he aimed up at where it came from and fired. After a few seconds of this another loud bang came and a Hell Knight came crashing in from above, immediately charging as soon as it landed. With barely anywhere to go, the Doom Slayer double jumped straight up before kicking off the door frame behind him, switching to his Super Shotty as he did. As he sailed over the demon’s head he unleashed two point blank blasts from the gun before landing on the other side. It was enough damage to bring the demon to its knees and he quickly grabbed its head from behind and snapped its neck, the beast dropping health as it fell. He looked up at the gaping hole in the roof before jumping up and grabbing the ledge, quickly pulling himself up on top of the car.

He quickly surveyed the area as he felt the wind whip by him, seeing a large swarm of Lost Souls, Cacodemons, and the occasional Summoner approaching both from the sides and from ahead. Already a large amount of them were attacking a pale blue energy bubble covering both the first car and the steam engine, cracks beginning to form on the barrier, some healing slowly but nowhere near fast enough to deal with the Cacodemons bile, the Summoners hell waves, or the Lost Soul’s kamikaze attacks. Even worse, some Summoners were calling forth ground troops like Hell Knights and Hell Razers. Wasting no time, he switched to the gauss gun and charged to the front, charging his precision bolt and firing at the Lost Souls that were closely grouped together with other demons, the Volatile Discharge causing them to explode and damage other demons nearby upon their deaths. After a few shots of this the Lost Souls began to divert their attention to him and charging as they screeched. He to a few more shots at them, their clumped groups making it easy to take out several of them at once when they exploded. Once they started to get a little closer he whipped out his super shotty, the blasts of buckshot easily able to take out several with each shot once they got into the the perfect range as he continued to charge forwards. Within only maybe seven or eight reloads of the powerful weapon, all the Lost Souls near the train were gone. There were more approaching from the sides and ahead in the distance, but he’d deal with those later.

Only three cars away from the front now, he decided to switch his focus to Summoners, as they were always the biggest pain in his ass, switching out for his rocket launcher and its lock-on function as he methodically began to pick them off one by one, the explosions giving splash damage to anything nearby. After a few rounds of this everything was now completely focused on him began to fire. Due to the massive amount of projectiles as well as the limited running space, he was forced to hang back and fire while dodging, not wanting to lose his unlimited ammo bonus by his armor taking too many hits. With a few more rounds he had managed to take out all the Summoners, just in time for three Hell Knights to make it over to him. Thinking quickly he jumped backwards into the train through the massive hole in the side of the train car, the three hulking demons following as he switched out for his chaingun again and backed into the doorway between cars, spinning up the barrels as he did. He ran backwards as they charged him, the closed quarters forcing them to charge him single file as he unloaded the unending stream of lead, the bullets passing through all of them, making sure he was taking down three ugly-ass birds with one stone. The one in front died within seconds, the next one following soon after. He stopped firing as he saw the third one fall to its knees, quickly rushing forwards and slamming his left fist into the back of its head before quickly following up with a right hook that cracked its skull open like a gorey coconut. He then dashed forwards until he reached the car with the hole and jumped back up to the roof.

He was immediately met with group of Cacodemons nearly upon him as well as another approaching wave of Lost Souls from the front. Already not willing to deal with this shit, he pulled out his plasma rifle and managed to get two of the four with as stun bomb, and then pulled out his chainsaw and shoved it into the eye of one of the others, killing it almost instantly. He then jumped onto one of the stunned ones, grabbing onto it from the side and slamming his fist into its eye, dying and releasing another stun charge that managed to get the other unstunned demon, giving him the chance to focus on the one that was already stunned as he shoved his eye fist into its eye. He then jumped onto the last one from behind, swinging around it before shoving his foot through its eye, killing it, before landing on the roof and pulling out his combat shotgun, quickly taking aim and firing an explosive shot into the group of oncoming Lost Souls, the explosion and subsequent cluster bombs destroying most of them in one blast before switching out for his Heavy Assault Rifle and quickly picking off the rest.

He adjusted his aim to the front, using the tactical scope to zoom in as he fired at the Hell Razers still near the front, headshots taking them down quickly. One of them managed to ready its charged blast and fired a steady stream of hell energy at him. The Doom Slayer leapt of the side of the car, still zoomed in and firing and using his In-Flight Mobility to keep him near the car. A few more shots took the last one down and he used his thrust boots to get back on the roof. With nothing on the train anymore he sprinted to the front right next to the barrier, using the scoped rifle to pick off any incoming threats, occasionally switching to the gauss gun and precision bolt to deal with the more hearty Summoners and Cacodemons. A few minutes later a tunnel through a mountain began to approach and he headed back to the car with the hole and jumped in. After a few minutes more the vehicle exited out the other side with no enemies in sight.

Stalwart sighed in relief at the lack of sounds of battle and looked out the window to see Canterlot in the distance. Unfortunately, rather than seeing the glorious city he was used to he instead saw the capital of Equestria covered in a veil of death, broken building, fires, red mist, and a golden bubble shield covering only about half of the palace visible even from all these miles away. He ordered the train conductor to bring the vehicle to a stop, the heavy machine slowly losing speed before stopping after a few miles.

Stalwart called his other guards over to assess the situation, when the violent sound of the door to the car ripping off its hinges caught everypony’s attention, some screaming in terror. It was the armored soldier from before who casually tossed the door aside before stomping towards the engine, ignoring everypony as he did.

“W-Wait. What are you-?” Stalwart barely had time to stutter out before he entered the engine.

“Hey, what are you doing in here!?” came the startled conductor’s voice. “You can’t just barge in here and-! Wait, what are you-!? Let go of me you piece of AAAAAH!” he cried as the elder earth pony was hurled out of the engine back into the front car.

Stalwart headed for the engine. “Hold it right there! This is-!” he began, only to stop as the soldier pointed one of his weapons right into his face. It was a small one, held in only one hand, but the humming noise and bright bluish-green light emanating from it did not make him feel any better about that. The soldier took a few steps forwards, Stalwart nervously taking steps backwards in response, until the armored soldier suddenly pointed the weapon down and fired, causing everypony to flinch and some to squeal in fright. Stalwart looked down and saw that the shot had severed the coupling between the engine and the front passenger car. Without a word, the soldier turned back and headed into the front of the locomotive, the machine slowly starting up as it continued down the tracks.

“You’re supposed to blow the horn to signal you’re starting up again! If you’re going to take my engine, you could at least follow proper procedure!” the conductor shouted angrily. Surprisingly, a few moments later, the vehicle did release one quick burst of sound and steam before it continued to pick up speed and ride away. “Tsk! Punk,” the conductor muttered.

“Sir… should we go after him?” one of the guards asked Stalwart.

The unicorn looked to Canterlot for a moment, remembering what he saw back in the train cars, and turned to his subordinate. “No… No, I think he’s going exactly where he needs to be.”

Author's Note

Sorry this took so long. I had some other stories and things to do first and then it took more time to come out due to, ironically, get a chance to actually play Doom. I hope the somewhat confined movement here doesn't affect the action too much.

As always, enjoy the chapter as well as the song inspiration for the title, straight from the Prince of Darkness himself: