The tower at the edge of reality - Magnus’ home and a research laboratory was busy, not that there was any time it wouldn’t be. The white-coated, blond unicorn archmage was pacing through the enormous, round library on the top floor as usual, magical diagrams and books flying in a dome around him.
“Void rifts, void rifts… when idiots try to ruin everything for the good fillies-” he stopped and facehoofed mid-sentence, “Holy balls, I must finally be going senile.”
In a flash of light, he disappeared.
When he rematerialized, he was standing on a king-sized bed inside a room slash library very similar to his own, although much smaller and with only one workbench, legs spread over the visage of sleeping and drooling purple alicorn.
“Hey, Starbutt!” he poked her. When Twilight didn’t react, he covered her nose. She just opened her mouth and resumed breathing freely, “Okay, mares are the one research topic beyond even my intellect,” gathering energy into his horn, he shot a small bolt of lightning into the tip of Twilight’s ear.
“AAAAH?!” she sat up, her horn shuffling the hair on Magnus’ neck as he narrowly avoided being run through, “Who- wha- why- where?” she squinted, immediately lighting up her horn, “Magnus?”
“Took your damn time, did you?” he walked off of the princess’ bed. Why she pulled the blanket up to her neck he would never understand.
“How did you get here?” she mumbled.
Magnus leaned backwards as if struck, frowning.
“The idea that just because you can only get into my pocket dimension only with my invitation and permission does by no stretch of the imagination mean that the same is true the other way around!”
“Alright, alright...” Twilight rubbed her eyes. If there’s something she’d learned during her time as the leader of Equestria, it was to focus on the substance of problems rather than the form in which they were presented, “What’s going on?”
“I remembered!” Magnus started pacing back and forth in front of her bed. Twilight knew the primal ex-alicorn of Magic enough by now not to interrupt him. Magnus was very easy to irritate, “I was the one who designed the seal and the gate!”
“Seal and-” Twilight mumbled before her jaw dropped, “You mean the thing Flow is trying to open?”
“Noooo, the original wax seals for enveloped and the gate to the BDSM sex dungeon under this room!” Magnus rolled his eyes, “Of course I mean the Herald’s seal!”
“That’s great,” Twilight couldn’t be sure whether Magnus was just being sarcastic or if he actually knew about her fun dungeon, and opted not to ask about it, “So, did you recall anything helpful?”
“Everything I recall is helpful. I don’t fill my head with garbage about the latest celebrity couples. Night-lestia my ass and the wish of many clop writers,” Magnus snorted in contempt at the question, “Anyway, back to the topic at hoof,” he waved his foreleg to dismiss everything that had happened until now, “Look, Starbutt, what do you know about entities we used to call Dark Travellers?”
“I… I think I read a mention in some really old transcripts, but nothing in particular,” Twilight furrowed her brows, trying to jog her memory and getting nothing. That in itself was almost unique, as she could usually fairly quickly recall some reference to pretty much anything. Becoming an alicorn had improved her already good memory, and she could always remember at least if she heard about something even when she couldn’t recall what exactly it was.
“Yeah, the last one we encountered appeared several hundred thousand years ago. Some absolute cretin was mucking around with void research and, as always, understood too late what he was getting into.”
“When exactly was it too late?” Twilight’s morbid curiosity joined her actual curiosity.
“At about the time half of his body got gradually disintegrated and the rest of him as well as his… castle, was it? Yeah, it was. So yes, about when his castle got swallowed stone by stone into the void rift. Good researcher, though. Evil, obviously, but that’s pretty much a prerequisite.”
“Back to the seal and the dark travellers, please.”
“Right, right, I can’t be remembering every idiot who got eaten by their own experiment,” Magnus shook his head, “So, you see, when you open a rift to the void, which means when you’re dumb enough to literally rip the reality you exist in apart, usually certain… manifestations can come through.”
“Manifestations that look like shadows with claws or teeth?” Twilight finally did recall something.
“Yes and no,” Magnus shook his head, “This kinda links to the beginning of the universe, and certain hypotheses about it, one of which is that the entirety of potential is this sea of energy we can’t measure, and somehow, under some circumstances, this potential transforms into what we call a reality - energy, matter, that fake thing we use to measure transformation processes and call time, gods, everything. Unfortunately, if you poke enough holes into the border of the reality, the pressure of the void becomes big enough to start ripping our protective shell apart and unraveling reality back to potential. Now, unlike classic portals, you can’t make one-way void rifts, so whenever you start messing around, there is a chance that something might slip through.”
“These… Dark Travellers?” Twilight gave it a shot.
“Not always,” Magnus tapped his chin while considering how to keep dumbing the information down for someone who had never done any research on this topic, “These void... fragments can make many forms, both living and non-living. The best known unliving form is the safest one to research - crystalline material called istrium, which retains its property of nullifying magic and in sufficient quantities even divinity. It all stems from divinity being part of one reality, namely its most basic form of energy.”
“Ohhhh… like Chrysalis’ old throne in the Badlands? So that’s why the chaotic anomalies couldn’t reach the interior of the hive...”
“Yep, that’s the biggest singular formation I know about,” Magnus nodded, “You can grow istrium using divinity to open certain void rifts if you know how. Of course, working with it is exceedingly difficult, as it absorbs energy, and in general you need divinity, magic, heat, kinetic energy, and many other kinds to change the form of materials. Of course, it also drains… vitality or lifeforce, you might say, because in essence it is supremely diluted divinity of this reality, so working directly with it isn’t exactly safe either.”
“Magnus, what about refined istrium? Not the crystals, but a silvery-white metal. I mean, crystal ponies have been using tiny crystal shards as power sources, and I’ve seen weapons made of refined istrium.”
“Here’s where we get to the ‘size matters despite what everyone says’ part of the discussion,” Magnus nodded approvingly again, “You see, as I said before, the bigger the ‘amount’ of void potential that gets through the rift, the more void atributes it retains. However, small amounts of void… can bend to the rules, the pressure of our reality, our laws of physics. Small istrium crystals turn into real crystals with specific structure that absorbs energy, but when they are full, they change to radiate it back. That’s why small amount of istrium helps forge magical items with great energy capacity that are easy to recharge. Same would be true with weapons - the natural unraveling aspect of the void would make those bypass magical and to certain degree even divine protections.”
“Wait a second,” Twilight realized something, “So using istrium weapons to fight shadows-”
“Nice try, but it would be effective. It wouldn’t make them stronger… most of them, which is where we get to the, for lack of a better word, living void intruders. As I said, small enough amounts of void bend to the pressure of our reality, which makes them part of our reality. That goes for the entities you called shadows, which encompasses several variants of entities about which I don’t intend to go into depth right now. To put it simly, they become physical and gain lifeforce, and thus grow vulnerable to normal weapons, draining effect of istrium, or other ways to influence reality like magic.”
“So… what you call Dark Travellers are the greater amounts of void seeping into this plane of existence, am I right?” asked Twilight, much furthering Magnus’ approval.
“Yes, and they are nasty. They take many shapes, levels of intelligence, or amount of power, but their entire reason for existence is to unravel any reality they get into. It’s not that they are evil or inherently malevolent, it simply is what they are. Their nature makes them completely immune to anything but the most complex and dense magic or divinity. In the ancient times of the first civilizations using wild magic and raw divinity unleashed by the divine wars, Void, Scream, and I encountered Dark Travellers the most often, and destroyed them. Thankfully, summoning them is exceedingly difficult. In fact it’s so difficult, that ‘only possible by sheer accident’ is more accurate.”
“Could you do it?” asked Twilight, eyebrow raised.
To her absolute horror, Magnus shook his head.
“Not on my own. I know how, but I don’t have the raw power anymore. If I opened a rift so large as to let a Dark Traveller through with any kind of certainty, I wouldn’t be able to hold it open for long enough before it swallowed me and likely the unfortunate country in which I tried to do so.”
“Okay, opening rifts isn’t our goal anyway. How do we stop a creature like that?”
“As I said, Void, Scream, and I used to do it. I had the ability to weave magic complex enough to affect them, Scream had the divinity and magic skills to assist me, and Void… Void was a unique alicorn in all respects, much like our sister he had to kill. Just like she was the alicorn of Life, he was the alicorn of Death, and there is nothing that is endless, not even the Dark Travellers. That’s how he figured out the power of true death, something no one else ever did,” Magnus took a brief pause and sighed, “Who am I kidding? Void fought them on even grounds, we just assisted, we watched his back, and we gave him that little push he needed to break the balance of power. I miss him...”
“Do you think this Flow is a Dark Traveller?” asked Twilight, “I mean, if we presume that his irresistible attacks are indeed him opening small void rifts.”
Magnus pouted, and eventually slowly shook his head.
“I… don’t think so. If you ever meet one, you’ll understand. They have this sort of presence around them which bends reality. Flow didn’t have anything of that sort. He’s probably just some schmuck the Herald is using to break the seal.”
“Wait, how do you kow that Flow doesn’t possess this presence? You haven’t seen him, have you?”
“Sure I have,” Magnus smirked, “I asked Kronos to take me back in time to show me the massacre of one of your secret bases.”
Twilight’s jaw dropped. If they had the help of the alicorn of Time, then…
“You know, if Kronos is involved, why can’t we just go back in time and kill Flow, or at least figure out where he’s operating from?”
Magnus huffed indignantly.
“Well that never occured to me for some reason. Should I slap you now or later?”
“Less threats, more explanations. I don’t have the alicorn of Time as my little helper, so don’t get all snarky.”
“Okay, to point one - no, we can’t just kill Flow in the past, because we would create a branching timeline without him, but we would still return to the timeline where we’re now. And as for point two - Kronos can’t find him. The only reason we could see him was because we knew from you when the massacre happened. In the end, he opened a void rift and went it. We couldn’t track him afterwards.”
“Great, so even the alicorn of Time can’t find this guy. Whoever that Herald creature chose to do its bidding, it was a good choice...” Twilight sighed, “I understand that knowledge is power and that I know much more than I knew an hour ago, but I could really use some actual good news.”
“Oh come on,” Magnus smiled, “We know who the enemy is-”
“Not until you actually tell me something. I understand that this Herald creature is a Dark Traveller, but that’s about it. Why is it sealed rather than destroyed like the others?”
“Hmmm, perhaps I should have started with that,” Magnus cleared his throat, and whistled innocently, “Well, there was one Dark Traveller we couldn’t destroy. It was special in some way, as it didn’t attack us directly, it simply opened rifts much faster than any others. We were afraid that using true death to fight it would only weaken reality faster, so Scream and I crafted an elaborate seal across this plane as well as the mirror world to layer reality on the herald to stop its powers from working. The only ones who knew about it were Kronos, I, Void, and Scream. Flow certainly didn’t visit me or Kronos, and the other two are gone, so whatever Flow is doing with the seal keys isn’t going to work. Not to mention he’d need to find the ones scattered all over the mirror world as well. What’s most likely to happen is that he tries to open the gate with this world’s keys and then stands there blinking like a total idiot when nothing happens.”
“I find that too good to be true,” mumbled Twilight.
“You’re not talking to some amateur, but to the best damn mage and researcher in the whole universe,” Magnus stared at her, daring her to say something against his statement.
Twilight took a deep breath to clear her head, and then slowly breathed out.
“You know what? With all that mess surrounding Zebrica, I needed something even remotely positive. Thank you,” she smiled at Magnus, which seemed to genuinely take him by surprise, “However, don’t be mad at me when I take it only as a sign we have more time than we expected rather than assurance that we are safe.”
“Obviously, because that would be straight up stupid,” with a smirk, Magnus teleported away.
Twilight plopped herself back on the bed, and closed her eyes. A good night’s sleep, even despite this interruption, would be her well-earned reward.