After a sharp bend in the road, the treeline suddenly receded, revealing a large grassy clearing, unusually flat for its mountainous surroundings. The road skirted one of its narrower sides, while its other end was made up by a small yet craggy cliff, split in the middle by a large dark hole. Old wooden posts were flanking it, and in front of them lay the shattered remains of decrepit, age-eroded gates. Numerous muddy tracks were leading from the road and across the clearing towards the gaping mouth of the cave.
“This is it, everypony. Keep sharp,” Opal Beam said as the first unicorns left the road and turned to follow the tracks. The squads broke the close marching formation, distancing themselves from each other as they went. All the guards were silent, wearing determined or even downright ferocious expressions and readying their weapons. His squad’s two wizards, instead, looked apprehensive yet focused, but while Star Swirl was clearly feeling better in comparison, even Sunflower’s fearful gaze was tinged with resolve as she stared at the dark opening ahead.
The silence, made even more oppressive by the monotonous sound of falling rain, bore down on the ponies as the first squad, led by the Lieutenant herself, approached the ruined gates. Keeper Nightshade strode up to her side, and a ball of bright bluish-white light formed at the tip of his horn, lighting the way. The squad, collapsing into a formation more suited for combat and the confined space, cautiously trotted into the mines, and the Keeper’s guiding light quickly vanished in its darkness, as if consumed.
The following squad copied the first’s motions, with the exception of Dawn Gleam prudently hanging back instead of going in front. His glimmering orange light, too, vanished into the darkness. Not a single sound came out of the cave mouth, not even the distinctive clip-clop of armoured boots on rock.
Opal Beam’s eyes darted along the trees on either side of the clearing. He could almost feel that something was not right. It was all too easy, all too according to plan. Nevertheless, he could spot nothing wrong as the ponies continued on ahead and another squad was swallowed by the cave’s gloom.
Nothing wrong, except for the unsettling way the ponies just disappeared into the darkness. There should have been something. Darkness couldn’t be so... solid. He motioned for his squad to slow down, and seeing that, the officers behind him followed suit. Oblivious to that, the fourth squad entered the mines, obscured by shadow just as rapidly as the others before them.
As they did so, Opal Beam became aware of some sort of buzzing at the edge of his hearing and once again looked to the trees, but they stood around the clearing like a gloomy wall, betraying nothing and hiding everything but the sky above. Beside him, his colts also started to scan the surroundings in alert.
And then a flash of green illuminated the treetops, immediately followed by a glowing cone of the same colour hurtling from above them and into the clearing at great speed, straight towards the squad behind. Opal Beam managed to let out a cry of “DISPERSE!” just before it impacted against the ground in a burst of light and a shower of muddy grass, barely missing the squad’s sergeant.
Even as that cone sped across the clearing, more flashes followed, and the sky above was suddenly filled by a dozen more, flying at the ponies in the middle of open ground. Opal Beam whirled around, horn coming aglow with magic as he tried to think of a suitable spell while shouting “I said disperse! Whatever it is, don’t let them hit you!”
Moments after that, another mysterious cone of green emerged from above the cliff in front of them and shot right at where Iron Vein was standing. With unexpected agility, the stallion leapt aside, and the cone crashed into wet ground, throwing up a splash of dirt and leaving behind a rough crater in the soil. Opal Beam quickly shifted closer to check it, a stunning spell at the ready.
Inside the shallow pit was a shape, ponylike in size and form, crouching forwards with its head pointed into the mud. It was dark grey in colour, turning deep glossy blue along the back, from which sprouted tattered insect-like wings. It had a ridge of webbing where a normal pony’s mane would have been, as well as a semblance of a tail made of the same tissue. What could be seen of its legs was riddled with strange holes of uneven size and shape, some of them creating sharp and pointy edges.
Before Opal Beam could do anything, the creature sprang up and twisted around to face him, opening eyes of solid cyan. Its head was also ponylike, but adorned with a slightly curved and very sharply-pointed horn. Unevenly-ended tubes, looking somewhat like broken vials, jutted out of it where the ears should have been. It snarled, baring sharp, dangerous-looking teeth and producing a warped hissing growl, and leapt, not at Opal Beam but towards Sunflower, who stood transfixed with fear.
He tried to intercept it with the spell he had prepared, but the beam of magic it produced went off the mark. The creature bounded past him and right towards the young mare, opening its terrifying mouth and raising its jagged hooves—and was met by a mace wreathed in a pink haze, swung from the side directly at its muzzle. There was a sickening crunch, and the strange beast collapsed to the ground. Not taking any chances, Iron Vein followed through with a mighty buck, producing another wet cracking sound. Sunflower looked nauseous at the sight.
Opal Beam tore his gaze away from the defeated attacker just in time to see the squad that was ahead of them, without its wizards, gallop by away from the cave. Looking at their apparent destination, he saw chaos. Green flashes and speeding cones of light coloured the sky above the clearing, joined by black shapes similar to the creature Iron Vein had struck down. they spilled out from among the trees in considerable numbers, filling the air with noise akin to that of dragonflies, but magnified hundredfold, drowning out most other sounds except for their own shrill, hissing growls and roars. The beasts were converging on the two rearmost squads, already outnumbering them at least three to one, and while it was hard to see what was happening there due to the sheer number of black bodies clogging the intervening space, it was clear that the ponies were in trouble. The unicorns closest to the beleaguered guardsponies rushed to their aid and into the thickening swarm.
And behind them was the entrance to the mines, with the other four squads inside. His unicorns were the only ones remaining nearby. Thoughts clicked into place in an instant: they had to stop these things from going in and ambushing the lead ponies.
“Everypony, keep them away from the cave! Don’t let them get in!” he ordered.
A bright orange bolt flashed into existence to Opal Beam’s right and struck one of the creatures flying by, causing it to tumble and fall to the ground unmoving. It was Star Swirl, standing firm with a concentrated, determined expression and without a hint of apprehension, already aiming another spell. Five creatures turned in midair towards him, only for his next burst of magic to blast one away. The rest quickly closed the gap between them and Star Swirl, only for Thistlethorn, Iron Vein, Meteor Shower and Comet Trail to intervene and engage each one, leaving the apprentice wizard free to fire. Another dark beast tried to flank him as the squad fought, but Opal Beam sent it hurtling into the rocks with a forceful knockback spell.
In a few moments, the four creatures were on the ground or trying to flee, and Opal Beam looked to the swarm that had surrounded the rear squads. The black beasts had tied everypony down. Opal Beam could see a guard set upon by three assailants, trying in vain to knock one off his back as another bit down on one of his forelegs and the third kicked at his face, bringing him down and out of sight before Opal Beam could cast anything. Beside the hapless pony, a wizard was being bogged down by numerous monsters attacking from all sides. Opal Beam hastily fired off a stunning burst, hitting one of the creatures, and the wizard’s own magical strikes took two more out, but an airborne beast fell upon the wizard’s head and dragged him down.
He loosed several bolts of magical energy at the swarming monsters; next to him, Star Swirl was doing the same, their magic colouring the immediate surroundings in shades of blue and orange. Each hit blasted one of the beasts out of the air, but it did not seem to make any difference—there were simply too many. All four squads that were behind theirs had already been drawn into the fight, and were clearly losing.
Just as Opal Beam thought that those creatures were somehow leaving his squad alone, a lot—at least more than a dozen—broke from the swarm and sped towards them. Himself and Star Swirl turned their fire on them, but the attackers seemed to have learned from the others’ example and weaved out of the way, only two spells finding their marks. Once again, the other members of the squad stood to meet the charge—Iron Vein, Meteor Shower and Comet Trail raised their shields as one, while Thistlethorn stood by the still terror-stricken Sunflower’s side, ready to catch the first monster on his blade.
Three of the monsters crashed into Iron Vein, two of them caught on the shield while the third fruitlessly scrabbled at his thick armour. Comet Trail’s shield was knocked out of her magical grip by the force of the things’ assault, but her own suit of heavy plate did not offer so much as an unguarded chink to their jagged hooftips. Meteor Shower’s spear went right through one of the beasts’ hole-ridden legs, forcing him to fight for the weapon’s possession while trying to fend off three more with his small round shield and wildly kicking legs. Thistlethorn was being attacked by two, successfully drawing them away from Sunflower, but they proved to be exceptionally agile: the wiry unicorn and the two dark creatures kept dodging each other’s attacks, as if engaged in an insane dance. Finally, four creatures attempted to outmaneuver Star Swirl’s bolts of magic with two drawing his attention with swoops at his head and two trying to strike from behind, but Opal Beam disrupted their tactics with quick, well-placed stunning spells after disposing of the only beast that had decided to go up against him.
They fought on. Several of the winged monsters fell to the guardsponies, but the rest were proving to be much harder to take down than the others before. The creatures kept dodging and taking careful yet precise swipes when the ponies’ guard was lowered, but did not seem intent on ending it quickly.
There was obviously some tactical reason for this, Opal Beam thought as one of the things switched its attention to him, keeping him occupied but not trying to overwhelm him. After some time it grew more reckless and came into reach of his hindlegs, and after he sent it arcing away, he risked a quick look around.
And there it was, the cause of the change in tactics: yet more dark shapes started to appear above the cliff’s edge, trying to stealthily fly down into the mine entrance behind their backs. Immediately, he turned about and unleashed a series of magical bursts upon them, and Star Swirl, noticing that, did the same. Taken unawares, many were struck and fell to the ground unmoving or were slammed into the rock, but the luckier ones dashed away from the cliff and across the intervening distance. Opal Beam barely had a chance to brace himself before one smashed into him, followed by another two.
The monsters abandoned their previous tactic as the failed stealth assault instead turned upon its foilers. All of them swooped in and tried to swamp Opal Beam’s squad, and while they were lighter than ponies, their strength did not seem to match, and their numbers were making resistance very difficult. Opal Beam felt one of the beasts make a dent in the back of his armour with a sharp hook-like hooftip as two of them pushed him down to the ground. It was all he could do to kick back at them and keep them from latching on with their vicious maws until he managed to form an appropriate spell in his head. A forceful blast sent his assailants tumbling through the air and into other creatures, allowing him to get up.
Around him, his ponies were fighting for their lives. He could see Iron Vein bash an oncoming enemy in the muzzle with his shield while trying to shake off three others hammering on his armour. Star Swirl was with his back to the giant stallion, while Meteor Shower stood beside him with his recovered spear but missing the shield, just barely keeping their attackers at bay. In between them was Sunflower, trying to press herself as deep into the ground as possible. Comet Trail and Thistlethorn were off to the side, the swordspony still dodging and weaving among the creatures despite their best efforts and the heavily armoured mare struggling to move under the weight of four monsters hanging onto her and trying to get at unprotected spots. Before Opal Beam could help any of his ponies, however, the beasts thrown off by his magic leapt back at him, and all he could do was keep them from overwhelming him again.
Just as he began to flag under the relentless assault, a flash of bright purple illuminated the scene, immediately followed by a bolt of magic exploding in the middle of the swarm. One of them, in the middle of a leap that would’ve landed it onto Opal Beam’s back, momentarily disappeared in another flash and emerged hurtling backwards at great speed. The unexpected barrage continued, and the wall of monsters around him quickly broke and receded.
The source of magical strikes revealed itself to be Lieutenant Moonlight, standing in the entrance to the mines, horn low and glowing bright. Purple bolts rapidly leapt off its tip and impacted against the creatures, driving or violently throwing them back. As the last of the beasts clinging to Iron Vein’s armour was flung away, she started towards Opal Beam’s ponies, continuing to pelt the enemy with magic as she went. The tide of battle turned with her help, the rescued members of the squad joined in, speeding up the beasts’ retreat, and more guards cantered out of the cave as she approached him, taking position around the entrance and launching arrows and magical attacks at any approaching monster.
“Sergeant, give me a report!” Moonlight shouted over the noise of continuing combat.
“Surprise attack, those things came from all sides! Rear squads got bogged down!” he responded. “They tried to distract us and get inside, but we drew them off!”
“Good! We wouldn’t have fought them off if they got reinforcements!”
“Reinforcements?” Opal Beam took a closer look at the Lieutenant. She was bleeding from a cut across her flank, and the plates covering her sides and back were bent and dented in places. “What happened?”
“I don’t know what happened! Half of my ponies suddenly attacked the others! We fought back, and they- they turned into these things!” Her voice was uncharacteristically fearful. “We brought some down and others fled deeper inside.”
Before Opal Beam’s already reeling mind could take that in, another unicorn galloped out of the mines. His horn was wreathed in magic the colour of morning sun, and his cape streamed behind him like a flametongue. The magical glow then erupted with a ball of fire that streaked through the air and right into the middle of the swarm above the rear squads, exploding with a loud boom and the roar of rushing flame, turning a part of the sky into a fiery storm. As the shrieking monsters recoiled from the heat and tried to beat down the magical fire enveloping them, Dawn Gleam continued on at a canter, and after a few moments sent another mighty fireball at the enemy. The beasts quickly withdrew from the now dangerous air, but did not flee - instead, most of them made for where the squads were, landing in a veritable pile of bodies.
The Keeper moved past the group of ponies, monsters scattering before him in fear of his power. Another fiery blast leapt off his horn and into the air, bathing yet more dark creatures in flame and illuminating the clearing. Sunflower finally raised her head from the ground just in time to see this, and immediately screamed at the top of her voice: “Dawn Gleam! Dawn Gleam!”
The unicorn turned his head to the sound of her voice, the magical glow draining away, and then took a sharp turn back. Opal Beam and Moonlight both watched him run up to the young mare cowering on the muddy grass and stop in front of her, exchanging words impossible to hear over the sound of the beasts seizing the moment and taking to the air again. Star Swirl and the other guardsponies were doing their best keeping them away from the squad and the mine, but the ones thus driven off headed to the rear squads instead.
All that Opal Beam managed to get himself to say on the wizard’s sudden disengagement at such a critical time was a flat “What the hay.”
Dawn Gleam raised his head and glared at him, stating “I’m not leaving her again!” Meanwhile, most signs of struggle from the heap of monsters where ponies used to be in the field were fading very rapidly.
“Sergeant, get out there and save them, right now! We’ll take care of defense!” the Lieutenant commanded, echoing Opal Beam’s own thoughts. She then gave the Keeper a glare of her own, intoning rather coldly: “I hope we don’t lose anypony because you let those creatures rally. And I hope you can still cast spells without leaving her.”
Opal Beam did not need to repeat Lieutenant Moonlight’s order. The squad, Star Swirl included broke into a gallop as one and rushed towards the dark mass of monsters. Despite what he’d seen them do to the others, and despite the very unfavorable odds, he was not afraid—his brothers and sisters-in-arms were there, amidst the enemy, and he was not about to let them die, not without doing everything in his power to help them. Besides, he’d been given an order, and orders were to be fulfilled. This steeled his resolve as he gathered his strength and magic, shooting stray beasts out of the squad’s way together with Star Swirl as they built up speed.
Halfway across the clearing, he noticed a group of monsters split from the rest and fly towards the trees with the motionless body of a wizard dangling from their hooves. He turned to follow it and was about to slow down to take better aim when Star Swirl called out “I got this!” Glancing over his shoulder, he saw the apprentice wizard come to a halt and start casting some spell, and so continued the charge, certain that his friend could handle it.
As they got closer to the dark swarm, many of the things turned to them, baring long, sharp fangs. Some attempted to take flight, but a powerful fireball roared across from the cave and set the air above on fire once again, and at the same time, a thin beam of orange magic connected with the group attempting to carry away a pony, causing them to plunge down. Everypony readied their weapons and shields, tightening their well-practiced telekinetic hold and positioning them firmly in front of themselves. Opal Beam himself prepared the perfect spell for such an occasion and readied himself to pour as much power into it as possible.
The force of the ponies’ impact alone was enough to send the front row of the monsters crashing into the others or even fling them over. Opal Beam’s overcharged knockback spell, however, outdid everypony, ripping into the creatures’ ranks as he set it off just as he reached them, sending at least a dozen closest beasts hurtling off to the trees and even more slamming into others. The ponies pressed their advantage before the enemy could recover. Weapons and armoured hooves fell upon the dark things like a deadly hailstorm, accompanied by cracking noises and terrible bloodcurdling screeches, and any attempts at retaliation were met with shields or deft dodges. Covering each other’s sides, the guardsponies steadily smashed through the monsters, causing the throng to part. Few dared to take to the air, however, for fireballs continued to light up the sky and strike without fail. Under the brunt of the unicorns’ onslaught, the beasts began to disperse, running into the shadows between the trees.
As the sea of black bodies receded, many of their number were left lying on the ground, battered and charred. The ponies Opal Beam came to rescue were among—and in some cases underneath—them, only a few still able to sit up after their assailants abandoned them. Several guards were partially covered in some sort of green substance, but he didn’t have time to take a closer look, far too focused on peppering the remaining dark beasts with bolts and beams of his light blue magic. The tide seemed to have turned completely—the clearing was becoming considerably more free of the attackers by the moment, through the concerted efforts and apparent tactical superiority of his unicorns and the others covering them from afar.
Opal Beam looked over the formerly cozy clearing, now strewn with bodies of the strange beasts interspersed with those of ponies. There were more than three times as many fallen beasts than unicorns, and the latter, for the most part, did not appear to be dead—most of them were groaning in pain and trying to move. He did not dare lower his guard to check on them, as the creatures responsible for their injuries were still nearby, but he gave the signal for Meteor Shower and Comet Trail to do so.
The patch of sky above turned a venomous green. Glancing upwards, Opal Beam spotted the already familiar cones—more than twenty—tear out of the clouds and speed directly downwards. Of course, he thought, it couldn’t have been so simple. They were in a perfect position for such an attack. There was no time to run.
“Protect the wounded!” he yelled, darting to the side of a nearby motionless guardspony. “Barriers up!” He planted his hooves firmly onto the ground by the pony’s side and started powering up a barrier spell.
Burning pain pierced his flank, causing him to yelp and twist around. The unicorn, unmoving just moments before, had leapt up with a sword in his teeth and jabbed it into Opal Beam’s right rear leg. Swiftly pulling the weapon back out, the guardspony tried to slash at him, but was countered with a swift kick to the jaw with the other leg. Wincing as he had to lean on the injured limb, Opal Beam watched a rapid change come over his attacker: just after his kick connected, the pony’s head flickered with green fire and turned into that of one of the beasts; the flame zapped down the rest of its body as it arced backwards from the force of the kick, and it fell to the ground as an undisguised monster, as motionless as it was moments before.
Straining to block out the pain in his leg, Opal Beam finished the spell, and a half-translucent sphere shimmered into existence around him. He cast a glance to the others only to see that Meteor Shower and Iron Vein had also been ambushed by impostors, and then the aerial charge hit.
Tremendous force smashed into his shielding spell and its feedback hit his head like a hammer, causing a blinding, disorienting flash of pain; the magic flickered and waned, but did not give way. Two dark shapes slid down along its outer side, and multiple splashes of green light filled the surrounding ground as other beasts missed their mark. Once the green fire dissipated and the pain in his head lessened, Opal Beam let the spell vanish as well. The two monsters that hit it seemed to be stunned, and he delivered a couple of precise kicks to each to be safe; some of the others sprang up from their impact craters, and while he was ready for that, his injury hampered him, and so he tried to intercept them with simple spells before they had a chance to attack. This was made a lot easier by the apparently unscathed Iron Vein, who stepped in from behind him and mauled the remaining creatures back into the mud as they approached.
After the last enemy attacking them had been dispatched, Opal Beam turned around to see how the others weathered the attack. Comet Trail was in the process of finishing off an attacker of her own, but looked no worse for the wear. Thistlethorn was surrounded by several newly defeated monsters and on guard for more, warily scanning every direction. Meteor Shower was nowhere to be seen.
Opal Beam called out his name, but no response came.
“Where is he? Where was he standing?” he asked, and Iron Vein pointed out a spot farther out on the battlefield, starting towards it right afterwards. Opal Beam began to walk there as well, slowly due to keeping the weight off his injured limb and the many fallen beasts littering the intervening ground. Comet Trail passed him halfway, hurrying to her brother’s side, and immediately upon reaching it, she launched herself into a full gallop towards the entrance to the mines.
“Healers! We need healers here, right NOW!” she shouted as she went, and Opal Beam’s heart sank.
Making his way past Iron Vein’s massive form obscuring the place, he was greeted by a grim scene. Meteor Shower lay in the dirty mush the ground had become, drawing in shuddering breaths. His shield was on top of him, a gaping hole nearly splitting it in two, and from that hole protruded the body of one of the dark creatures with its head stuck under the shield and the rest splayed to the side. Iron Vein tugged at it with his magic, and it fell away together with the shield, revealing an even more gruesome sight—the fallen stallion’s side had been crushed together with his armour and pierced by the monster’s horn, and blood was seeping from under the bent metal and into the quickly reddening dirt underneath.
Opal Beam twisted around in an attempt to look at the battlefield behind, unthinkingly shifting onto his injured leg and wincing as the dulling pain spiked again. At least the devious bastard didn’t hit the bone.
“Urgh. There must be a healer somewhere around here. Iron Vein, could you?” he asked through clenched teeth, and the giant unicorn rushed off to search just as Thistlethorn came closer.
The swordspony looked at his fallen squadmate, finally passing his judgement with a terse “bad” and returning his wary gaze to the trees, which were surprisingly devoid of any enemy activity. In fact, the nightmarish creatures seemed to have disappeared as quickly as they had rushed in, with the exception of the ones felled in combat.
Rhythmic hoofbeats came from the direction of the mine, heralding the arrival of two unicorns in white hooded cloaks escorted by Comet Trail, two other guards and, rather unexpectedly, Dawn Gleam. One of the healer ponies immediately knelt before Meteor Shower, horn flaring with magic as he urgently cast something, while the other cantered towards one of the wizards.
The Keeper approached Opal Beam. “Sergeant, I believe I need to apologize for committing that tactical mistake. I feared for my apprentice. I should have known she is not yet fit for such tasks,” he said, looking at the overwhelmed members of the rear squads.
“It doesn’t matter. You helped us with covering fire,” responded Opal Beam flatly, the intense focus of combat draining away from his mind to be replaced by shock and pain from every injury he’d sustained, leaving him lightheaded and in no state to argue or judge. “Please, aid the wounded if you can.”
Dawn Gleam nodded and began to trot away, but turned his head back to Opal Beam and added something which he had already figured out for himself, which presented itself to him in the clearest possible way.
“Those things can assume the shapes of others. They are changelings.”