Prompt: The door flies open when you arrive and a young unicorn with blueish mane walks into your office.

>This is how you were meant to burn; fast and bright and hot, like a runaway plasma spell eating through plate metal.
>Not like a boiler, slow and steady.
>The coals can only smolder in your guts for so long before burning through.
>And a mare can only take so much before cracking.

****

>You remember the day you were a young unicorn, walking into the office the letter had directed you to.
>Back then, you hadn’t known the envelope with the logo of two horns crossing in front of an eye wasn’t a simple work offer going out to all unicorns registered in the system.
>You hadn’t known what lay ahead.
>You only knew what lay behind: a canceled project, two years of forging spells in a high-security lab complex, and a skillset much too specialized to ever get out from under again.
>Going into public service would promise more of the same for stable pay.
>It seemed like a good idea.

>The first hint that you might have been wrong was the address you were directed to.
>You’d been to the Royal Castle before, of course, but only as a tourist.
>The fifth hint came in the form of two armored unicorn guards shifting into combat stances when you entered a small antechamber.
>You managed to float the letter out of your saddlebags without tripping over your own legs.
>"Do a twirl," one of them instructed, and you were too dumbfounded to question the order.
>A mirror on the side wall reflected a mare with a blue coat and light-blue mane, feeling silly spinning around her own axis.
>Once her cutie mark faced the guards—a white, star-shaped spiral—they relaxed. 
>"Standard protocol for castle security," the stallion handed you back the letter. "Head on in."
>The door he pointed to was much larger than it had any reason to be and was adorned with intricate lines of a blackish metal you didn’t recognize.

>The office was murky but well organized.
>A tall mare sat behind a neat desk, what little light there was getting lost in her coat.
>You realized she was an alicorn.
>"Don’t," she said in a voice made of equal portions velvet and ice when you tried to take a bow.
"I’m sorry. My name is–"
>"I know who you are. Sit."
>You sat.
>She studied you in silence for a minute.
>"I guess you’ve got some questions?"
"I kind of decided to just go along with it at some point."
>"What point was that?"
"Well, when I announced myself at the castle gate, the directions to the office included short-range teleportation, crossing an improperly-marked Ley-line barrier, warnings of self-rearranging architecture, and twelve sets of stairs. I got lost somewhere near the kitchens only to be found by a unicorn filly who guided me after taking the liberty to scan my bags for candy with a radio-imaging spell I’ve only ever seen from ponies ten times her age. My kidneys look fine, by the way."
>You remembered to take a breath.
"I’ve found no less than three doors sealed with alpha-level curses just sitting on the walls, and I’m pretty sure someone placed a reality-bending or cognitive hazard spell on the master staircase because I kept coming out at the bottom again."
>You shrugged.
>It was the only thing you had left to do.
"I do have questions. But it feels like I’ve missed the window where asking them makes a difference by a few corridors."
>The princess leaned back in her chair a bit.
>"And you still want the job?"
"It would be a waste not to go through with it at this point."
>"What’s your experience again?" 
>She knew of course, but she wanted to hear it from you.
"I got a degree from the Institute of Æther Technology in experimental spellcraft. I did a rotation in the Magical Defense Force afterwards and got scouted for a research project by a private company. They got canceled a few months ago. I got the announcement you were hiring." 
>"What was the project about?" 
"I’m sorry but that’s classified information. Something something corporate secretes there are eyes and ears everywhere."
>"It wasn’t about high-energy æther warfare?" the princess raised an eyebrow.
>She politely gave you a moment to make sure your heart was still pumping.
>"So, how’d it go?"
>Now you were half torn between running for the door and running a sweep for audio-surveillance spells.
"I’m… I was a technician. I came up with spell concepts and worked on ways to implement them for the casters to try."
>"And what about the fact that you pulled those off yourself while doing that? And that you melted an entire targeting facility with a miscalculated las-burst?"
>Something in your stomach gurgled. 
>"I can get access to most files, you know," the princess almost suggested a smile.
>She rose from her desk and so did you, eyeballing the door.
>"I guess that should do it."
>To your surprise, she offered a hoof.
>"Welcome to the Adeptus Magia. I’m Luna, in case that wasn’t clear. You’ll make a fine Magos."
>Magos?

****

>Even though the sun has only just crept over the eastern mountains, the inside of the cave maze is already sweltering.
>It had been throughout the night.
>And the day before.
>It’s not the sun that dictates the temperature of the halls and winding corridors anymore but the days of magical warfare that have charged the very stone with enough energy to run a small city.
>The drafts gushing through the tunnels feel like firestorms being blown into your face.
>Nova spilled a gulp from her water flask into a particularly blistering corner yesterday and it actually sizzled.
>The rocks radiate punishment into the air, making it uncomfortable to stand, uncomfortable to sleep and eat, uncomfortable to be alive.

>They noticed you at last.
>For three hours you had followed the curve of a natural cavern without incident, creeping deeper into the labyrinth.
>A flash is followed by an explosion of superheated air somewhere in the back of the battalion, throwing ponies into the air with pained shrieks.
>The clicking rises again.

****

>It took you a long time to realize the reason Luna had hired you, more than your grades and references, was the fact that you followed the letter’s invitation away from the private sector and through the mess of a commute.
>The Adeptus Magia usually recruited directly from academia.
>And their approach couldn’t have been more of an inversion to that of the corporations hiding behind their confidentiality clauses and non-disclosure agreements.
>Instead of honing a few standardized formulas to extreme precision, most of the Adeptus' spellwork was custom tailored.
>Rather than flocks of casters with identical, uninspired perfection, the Magi were sharply attuned to their individual talents.
>Trading optimization for autonomy.
>Interchangeability for expertise.
>It resulted in the biggest clusterfuck of clashing doctrines you could ever hope to witness.
>And the occasional evacuation due to unforeseen interactions of haywire witchcraft threatening to vaporize the barracks.
>An entire sub-division was tasked with nothing but to provide the high-ranking members with the tools and ingredients they requested, a desensitized bunch of stallions and mares working out how to safely procure alicorn dust or pegasi skulls.
>The Adeptus Magia was also, as an afterthought to the chaos, the most effective magical fighting force you ever knew.

>You didn’t have the raw power of the Exterminatus squads nor the psycho-awareness of the grand conjurers.
>But you didn’t need it either.
>Over the course of your experiences, you had condensed æther in more varied and intimate ways than most unicorns alive.  
>Whatever natural ability you possessed you managed to amplify a thousandfold.

****

>They might have been changelings once, but they seem to have lost the ability to transform at some point.
>Their torsos are sleeker, their wings less developed, their heads flatter.
>They don’t speak any of the known languages but are able to communicate with sharp bursts of high-frequency clicking.
>The exoskeletons shielding their bodies have wet, oily-slick sheens to them, boasting magical protection rivaling the scales of the elder dragons.
>And their horns—long, knobby growths taking root deep in their squat skulls—are capable of channeling magic usually reserved for veteran unicorns.

>You quickly learned not to trust your telepathy.
>As useful as it is for keeping battalion coherence, it has to be considered a shout into the æther rather than a whisper at the best of times.
>And a megaphone at the worst.
>The enemy ambushes have precisely countered your plans too many times.
>Too many scouting teams never made it back to the bulk of the force.
>On top of it all, some of the battalion’s younger members, the ones that were forced to come along out of necessity instead of strategy, have started to show signs of mental fatigue.
>It takes time to get used to the voices inside your head that aren’t your own, after all.

>"There’s a small cocoon-cluster ahead," Nova explains, etching lines of red light into the wall.
>They from a rough map of the shafts and tunnels you managed to get a glimpse at.
>A small group of Magi is huddled around the drawing.
>"How much further to the hive?" Selena asks.
"We don’t know. They tried long-range scanning spells on the mountains a few days ago but it wasn’t conclusive."
>"We have to be close by now, right?"
>No one is confident enough to agree with her.
>You’ve been proven wrong before, with ravine drops and dead ends forcing you to double back for half a day, fighting off the swarm.
>"Well, we know we’re on the right track at least," Nova jokes, slapping Selena’s shoulder. "Their numbers keep increasing."
>There are a few smiles.
>Most of them are forced.

****

>You remember wondering about the bells.
>It wasn’t the top of the hour, and Nova assured you that it wasn’t some official function you had managed to forget this time either.
>The city stretching away under the castle’s watchful gaze was still half asleep in the morning sun.
>Yet the bells wouldn’t stop ringing.
>The wind carried the slow chimes along narrow streets and over coppery rooftops.
>They crept over the bulwarks and overgrown courtyards, scaling the high walls all the way to the upper balconies.
>If you squinted against the early light, you could just make out the First Star herself on the southern tower’s gallery, searching the alleyways with her gaze.

>"You think it’s a drill?" Nova brought you back to the ground. "Functionality test?"
>She still had the spear she was trying to poke through your shield spell with in her telekinetic grasp.
>So far it had held up formidably.
>A flock of guards was galloping along the wall, paying no mind to the two Magi fiddling with the potential energy to flash boil a sizeable portion of the brickwork.
"If it is, no one is in on it."
>"Or they’re just, you know, dedicated to their roles."
"I should probably start drawing this down."
>"Might not hurt to leave it up," Nova joked, but something in her voice was different than usual.
"If I lose control it’ll be enough force to topple a Solaris Engine exploding outwards."
>"We might need it."
>This time, she wasn’t even trying to sound like she was kidding.

>War had come to Equestria quickly and overwhelmingly.
>There was talk of invasion in the taverns and markets.
>The southern cities along the outskirts of the wasteland would already be burning.
>The pegasi Interceptors would be falling out of the sky like shooting stars. 
>You spent the days impatiently.
>Edgy.
>Waiting for news.
>Packing and re-packing your field kit.
>Waiting for the decision to be made.
>Waiting for the inevitable knock on your door.
>It came on the third day.

****

>The air is greasy with magic.
>Ice-bright projectiles chase each other through the hot fumes, explosions of light and fire and heat and death shake the ground like war drums.
>Large parts of the cavern’s ceiling have begun to loosen, crashing down into the ground with no care for sides or strategies.

>You allow yourself another breath.
>And bolt out of your cover into the open.
>A plasma beam splits the air over your shoulder.
>One, two lightning strikes leave your horn, crackling spiderwebs crawling through empty space and devouring whatever they find at the other end.
>You dive below bursts of witchfire, skidding towards a group of Otherlings Nova is holding at bay.
>She’s throwing out fast, red-hot lines of light.
>They’re not very precise but high-frequency las-fire forgives many sins.
>You fly past her, taking out stragglers with heavy pulse shots, recoil reverberating through your body. 
>Blowing through the fighting shapes and the globs of molten rock littering the ground, you dance deeper into the chaos.
>More magic.
>More death.

>Iona is surrounded by a cluster of glowing orbs lazily floating towards their targets.
>They ignite, and the cave is illuminated by a dozen dying suns for a tiny moment. 
>The light subsides, the heat lingers.
>Where a swarm of enemies was before, only the glittering ripples of stone burned to glass remains.

>Selena is standing still amidst the havoc, her eyes closed.
>To a bystander, it might look like she was praying.
>Two Magi are circling her form, nullifying incoming spells and protecting the senior caster with shields and counterbattery. 
>A hundred meters down the next tunnel, a giant, conjured beast is rampaging through the ranks of the enemies.
>Each swipe of its massive claws shreds bodies.
>Palpable tremors follow the strikes of its tail.
>The spells hitting its tough hide explode like high-energy fireworks.
>It lets out a deep howl before spewing liquid fire, setting ablaze cocoons and Otherlings alike. 
>Mind-slaved to its master, it has no will of its own.
>It knows nothing of the war.
>Nothing of the dwindling numbers of the Adeptus Magia.

****

>The scene of Nova’s death keeps playing in your head.
>A swarm of glittering stars in the darkness.
>Spears of white, angry light shredding past your head, crossing the room in the fraction of a heartbeat.
>The first pops her shield like a bubble of chewing gum.
>The second shoots off the reflector you manage to conjure into its part.
>The third finds its mark.

>You don’t have the luxury of remembering anymore.
>Of thinking.
>You just do.
>Every instinct is rewarded with the familiar, teeth-itching release of magic and another clicking abomination ceasing to exist.
>Every pause between reactions is filled with your screaming nerves trying to keep up. 
>It’s been hours since you’ve seen another Magos.
>You may very well be the only one left.
>It suits you fine.
>Less collateral.

>The explosion of the magical tripwire knocks the wind out of you for a second.
>Your hooves gallop over the slick stone before you know you leapt, chasing the blast echoing down the tunnel.
>High-velocity plasma shots zip through the dust cloud, leaving trails of green burning on your retinas.
>Your horn glows, hurling death at the emerging specters.
>The second tripwire covering your back blows right on time.
>An Otherling turns and your hoof meets its reflection in the greasy shimmer of its chitin carapace.
>The frenzied clicking around the corner reaches its crescendo when you jump out with a flock of tiny lights following your step, chipping rock and cauterizing flesh.
>An ion burst breaks forward, then another, each a slow, fat plume of stopping power trailing radiation.
>Two more Otherlings are torn apart before touching the ground.
>The way opens up into the largest cavern yet.
>You can see the hive.
>Further. 
>Just a little further.

****

>The giant structure, now that you’re finally able to see it directly, is much larger than any castle you’ve ever been to.
>Its many arms and sub-structures spiral and twist over themselves, softly shining from within. 
>If Nova was here, she’d probably call it pretty.
>It doesn’t matter anymore.
>A grazing kinetic spell took some of your right flank, leaving you limping.
>It makes no difference.
>You’re close enough.
>The tingling in the back of your head grows as you breathe deep.
>Warmth begins to spread from your horn.
>Lightning begins to crawl over your fur, raising the hair.
>Time is starting to slow.
>Reality is holding its breath along with you.
>The empty space between your heartbeats.
>The desecrated caves and tunnels.
>The corpses of your comrades.
>You think of fire.
>Of energy bursting out of its shell, tearing itself to pieces.
>The moment pools into place.
>And cracks.