Nopony ever truly appreciated the power of wanton destruction until they saw the evidence of it. The battle that had taken place here, Tarnish had trouble believing that there had been any victors. Had any survived? How had this ended? All of the unicorns had gone mad and… then what? Battled each other to the last, locked together in magic-induced hatred? The artificial ley line at least explained some of what happened here, with its power boost and its effect upon sanity, but the things that he and his companions were seeing, there would be no unseeing this.

The air was tainted with a musty, swampy smell, the scent of decaying vegetable matter. Some of the passages were impassable, even now, centuries later, and the tell-tale shimmering of magical radiation lingered, revealing pockets of magic gone sour. Tarnish had an almost-instinctual understanding of these pockets, these failed spells, these dud castings. In the wilds of Equestria and other places, animals might get pulled into these pockets and be mutated—or worse, multiple animals might be pulled into the pools of soured magic and merged.

These pockets of soured magic weren’t like typical pockets of magical radiation, not at all, and it wasn’t something his own poison joke magic could nullify, much to his own dismay. These shimmering, warping, glimmering pockets of magic were magically charged with the emotions that had spawned the spell, and had perhaps contributed to the spell’s failure. In his travels through the wilds, he had encountered these failed spells a few times. There was one near the Castle of the Two Sisters in the Everfree and it was a mild one.

Avoiding these magical hot-zones was becoming increasingly difficult and dangerous. Seeing them took sharp eyes, and sensing them required well-attuned senses. As for getting rid of them, Tarnish had no idea how such a thing might be cleaned up, and having talked with Princess Celestia once about it, neither did she.

Of course, his own Druid’s Grove was awash with magical radiation of a peculiar type.

“So many magical misfires in one place,” Rainbow Dash remarked while her eyes lingered on a shimmering patch of distorted light. “So, If I listened to all the boring stuff you’ve told me correctly, these are misfired spells… spells gone bad. Could Twilight cause something like this to happen? By accident?”

Tarnish nodded and passed Rainbow a camp cup full of steaming tea.

“So this can happen if a spell is interrupted,” Daring Do said to Tarnish while Rainbow Dash accepted her cup of tea. “Potentially, interrupting a unicorn’s spell might be more hazardous than letting them finish. That makes combat rather fraught with danger, don’t you think?”

Shrugging at first, Tarnish then nodded after thinking about it for a moment and he passed a second camp cup to Daring Do. “Sometimes, magic, once evoked, it can safely fizzle out if something happens. Other times, it can leave a permanent echo behind if the unicorn casting it has sufficient power. I learned that from Vinyl”—he gestured at his fellow unicorn, who was sipping tea—“she spent a lot of time pounding magical theory into my head, or trying to. I’m not very good at it, but she seems to think I am. I suppose that’s friendship for you, your best friends never stop believing in your potential.”

For a moment, it appeared as though Tarnish might have been left a little sad from his statement, but then he chuckled and tossed his head back. “It’s funny, I just don’t get magical theory very well, but if I read a book about plants, I pick up all kinds of scary knowledge… like, for example, calcium oxalate. It causes blisters, swelling and burn-like injuries on your skin, it’s even worse in your eyes, and it causes things like kidney stones. I could do bad things with plants the same way Vinyl can do bad things with magic. I think it all comes down to cutie marks. It’s just an opinion.”

“So, lectures about magical theory make your eyes glaze over and your brain turns off, but a lecture about plants gives you the observational powers of some cackling evil mega-genius.” Daring Do’s eyes narrowed and she blinked a few times at Tarnish. “Are you suggesting that cutie marks interfere with what we choose to learn?”

Wide-eyed, Tarnish shrugged. “Maybe? I think some of us can overcome it though.” With a blink, his eyes took on a heavy-lidded gaze, and he peered down into his own teacup. “I figured out how to weaponise crystalised calcium oxalate dust and I think I could modify some plants to spray particle clouds of the stuff. There are a number of plants that produce the stuff naturally. I’ve turned in my findings for peer-review. The review directors sent me a letter telling me they were intrigued, but also appalled and horrified by my findings. Apparently, weaponised flora isn’t something that ponies do and nopony knows what to do with my findings.”

Turning her head, Rainbow Dash glanced over at the magical anomaly in the corner of the room. It was a safe distance away, but it still worried her, as was evidenced by her face. The walls around it were warped, distorted, and the ceiling right up above it, the stone bubbled like porridge in a pot. After a few moments of silent staring, she returned her attention to Tarnish.

“So, a unicorn stood in that very spot, went to cast a spell, and either suffered a misfire or something interrupted the spell before it could finish.” Blinking, Rainbow’s head tilted off to one side, and her expression became one of fearful curiousity. “So now the magic is just… stuck there until it burns away.”

“More or less,” Tarnish responded and Vinyl nodded her head in agreement.

Again, Rainbow’s head turned and she cast her well-focused stare upon the boiling, bubbling ceiling just above the anomaly. She slurped her steaming-hot tea, careful not to burn or scald herself, and her eyes remained upon the focus of her fascination. She and her companions sat among the garbage-strewn wreckage of what might have been a laboratory, or maybe even a classroom, which was somehow fitting, given the educational nature of the discussion.

The swampy smell was growing stronger, and Tarnish began to suspect that all three pony science wings connected to the swamp biome. The earth pony wing had been sealed off, however, Tarnish was almost certain that this wing wasn’t. Moist, foul-tasting air assailed his senses, and this air was particularly foul in comparison to what he remembered when they had first encountered the swamp biome.

“Hey, Daring!”

“Yes, Rainbow?”

“Do you remember that big fight where somepony tried to drop that big safe on Tarnish and I swooped in and saved him?”

“Rainbow, what brings this up?”

“I dunno”—Rainbow shrugged—“just bored, I guess.”

“Ugh,” Daring groaned and she rolled her eyes.

“Hey, I’m pretty confident that I would have noticed a falling safe and saved myself.” Tarnish almost gagged on his own words while he pushed his way forward through a rubble-strewn hallway. “I did return the favour when you got that blinding dust in your eyes and somepony covered the floor in marbles.” It was a clever way to cripple somepony with super-speed, Tarnish was forced to admit. Still, it didn’t save said villain from getting a super ass beating, as he and Rainbow took their time in working him over.

“Yeah, but I’m still disappointed that I didn’t get a chance to see you try and walk over a floor covered in marbles, Big Guy.” Rainbow, grinning, gave Daring Do a sly look and nodded her head. Without warning, Rainbow came to a halt and her ears went rigid, vibrating on her skull. The smile vanished from her face and she shook her head. “We’re not alone.”

Tarnish, now also still, strained to listen, and he too heard something, a distant squelch. There was a hissing, sizzling sound, like oil in a hot skillet, and there was an acrid tang in his nose. Squinting, he began to look around, trying to find visual signs of trouble. The stone passages here were damaged and the rooms—if they could even be called as such—had collapsed walls, making them just misshapen extensions of the passage. The floor had puddles of stagnant water.

Coming around the corner ahead was one curious tentacle, which writhed and reached. Tarnish watched in horror as the owner of said tentacle began to also come around the corner. A pile of animated garbage, rotting vegetation, old bones, and some very visible spider’s legs. Part plant, part garbage, part rotting corpses, all horrifying eldritch abomination.

“Shambler!” Tarnish shouted and he yanked Flamingo from her sheath. Raising his shield, he began to retreat and he prepared the Bellringer to be fired.

Vinyl—moving in retreat—began to cast spell protections on herself and her companions, including a few draining acid ward spells, which would help resist acid damage. Setting a shambler on fire was a dangerous gamble, as the smoke could be even more fatal than the shambler itself.

“They’re eating her!” Flamingo shouted as she flew towards the shambler. “And then they’re going to eat me!” The unmistakable sound of heavy breathing filled the area, coming from the swooping sword. “OH MY CELESTIA!” The word ‘Celestia’ was long and drawn out in a weird way and Flamingo made a few faints at the shambler, engaging its curious, clutching tentacle.

The flying, seeking sword was tentacle-slapped by the shambler, and acid dribbled along the length of her blade. Flamingo began giggling, an unexpected sound, and she wiggled in the air while the acid sizzled along her length.

“Stop! That tickles! It’s like somepony blowing raspberries on my teats!”

From behind his shield, Tarnish began laughing at the absurdity of it all. With a nervous chuckle, he fired his weapon and much to his dismay, it did nothing. Now both laughing and annoyed, he began the task of reloading, and watched as Flamingo hacked at the shambler, which was squirting out spores. Not a good sign, not at all.

“Stay back!” he warned and he gave both Daring and Rainbow a meaningful glance.

A half-rotten unicorn skull emerged from the shambler’s body, hanging from a decomposed neck, and writhing with tiny, supportive tentacles. A vile green ray fired from the unicorn’s horn, which was countered by Vinyl, who raised a reflective shield. The green ray was reflected and bounced off to hit a wall, where it blasted out an enormous crater from the stone.

“WHAT IS THAT?” Rainbow’s shout echoed through the passages, becoming a chorus of curiousity.

After firing his weapon for a second time, Tarnish realised how futile it was to do so. The shambler was coming forwards, and Flamingo’s slices weren’t doing much damage. Vinyl wasn’t shooting it either and she was taking up an entirely defensive position at the moment. Reaching out with his mind, Tarnish tried to communicate with the shambler’s plant portions, hoping he could dissuade the eldritch entity from attacking him and his companions.

It was the worst mistake he could make.

There was an orgy of violence all around him and Tarnish cringed while ducking his head down. The air was cold, very much so, and he could see his breath. It was also thick with hurled spells, which sizzled, crackled, and flooded his nostrils with ozone. The screams of the dead and the dying were all around him, but there was something else as well.

“FIGHT FOR ME!”

The voice was everywhere and nowhere, it came from all around him.

“FIGHT FOR ME SO THAT I MIGHT POWER UP THE ANCIENT MACHINERY AND ASCEND! GODHOOD IS WITHIN REACH! SKYREACH! TO GRASP AT THE SKIES AND ASCEND! ASCEND!”

As the words echoed through the chambers, unicorns continued killing one another. The most awful of spells were being flung around, hurled, and Tarnish witnessed one unicorn that appeared to be turned inside out. Another spell exploded, causing the walls to collapse. There were two unicorns locked in mortal combat, their beams locked, each pushing at a magical nexus that swirled between them. Another unicorn killed one of the combatants, and the nexus went streaking off, flying into another group of combatants, killing many of them outright.

“I, SPEAR BREAKER, HAVE ALREADY RELEASED MY ARMIES UPON THE WORLD, AND NOW, I SHALL ASCEND AND JOIN MY SHRIEKING, FREEZING HOST! FIGHT FOR ME SO THAT I MIGHT KNOW PERFECTION! MANY MUST KNOW WAR SO THAT I MIGHT BRING LASTING PEACE!”

Encountering the lingering pool of rancid, corrupted magic, Tarnish’s innate magic kicked in to defend him…

The shambler exploded with bursts of blue light and then poison joke began to grow along its surface. Right away, it started shrinking, growing smaller, its wet, slick body appearing drier. The unicorn corpse fired off another necrotic beam, but Vinyl blocked it again. Tarnish, locked in a contest of wills with the shambler, continued to pour his essence in, though he had no realisation or understanding of doing so.

The shambler, an eldritch horror, tried to fend off the cleansing influences of poison joke. Motes of strange magic swirled around it, foul looking orbs of green light made slow, lazy orbits around the shrinking, withering body. Blue flames erupted from the poison joke blossoms, and this ignited the shambler, setting it ablaze with aetherfire. A terrible stench came from the blazing abomination, and Tarnish’s mind swam in and out of both the past and the present, witnessing the moment of Spear Breaker’s dreadful ascension. In his ears, he heard a horrific howling sound, a reverberating psychic echo from the past, a memory kept alive by the shambler. The keening wail left him feeling hopeless, cold, and it threatened to chill his heart.

A diseased yellow mist began to rise from the dying abomination and the blue flames burned brighter. Tarnish felt a peculiar sensation overtake him, a feeling of peace and calm that he associated with fulfilling his purpose, those moments when he was doing the will of his cutie mark. The feeling of hopeless despair fled from him, and thinking of his companions, he felt the warmth of life and friendship flow through every part of his being.

The unicorn corpse almost seemed alive now. It kicked and thrashed, raging against the coming end. Mouth opening and closing, it offered up the illusion of life. Whatever foul magics had animated it were now dying, coming undone, purified by the poison joke. Tarnish became surrounded by a nimbus of blue light, which crackled and arced with little lightning bolts that danced along his pelt.

The rotting corpse fell away from the shambler’s body, and once dislodged, the shambler ceased to be a threat. It became a burning pile of trash consumed by blue flame. As for the corpse, it began its rapid decomposition, and the tendrils of poison joke aided in the breakdown of the old, rotten tissues. The skull shriveled—like fruit left in the sun—and the bony structure took on a weird, unnatural appearance as it shrank.

With a sizzle, the remains continued to dissolve and the nimbus around Tarnish grew ever-brighter.

Author's Notes:

A lot is going on in this chapter. This one fight is just the first, more to come.