Back at Fillydelphia
A creature that resembled a pony only in the most vague of senses galloped towards the line Twilight's stallions had formed to hold this new variety of Zerg at bay. It was covered with plates of chitin and pulsing tendrils that snaked in an out of holes in the purple-furred flesh it still retained. Its lower jaw was split in half vertically and the two halves moved independently of one another as it charged, all of the original flat equine teeth had been replaced with jagged looking fangs. The guards opened fire on it immediately, a few shots hit it and the monstrosity exploded in a fireball of noxious gases and charred flesh.
Twilight Sparkle stared blankly at the crater where the infested pony had been, "that never happened in the simulation. The spell was supposed to recreate the exact effects of the weapons being used. I couldn't even detect any explosives in the ammunition, it was just plain metal!" As she was talking one of the guardponies in power armor walked slowly towards the hole in the ground, only to get jumped by another infested and tackled to the ground, before anypony could react the two of them exploded. "Who fired!"
"Nopony shot at it, their friend was in the way." Applejack replied to Twilight's inquiry. "It's like it just, blew up on its own."
"Why would somepony blow themselves up, that makes no sense? Unless..." Twilight turned to Spike, who was manning the communications rig considering how he was one of the few who had fingers. "What was it Fluttershy said about that voice she heard?"
"Uh, something about it sounding like it didn't care about its children. And how not even bees were so cal, call..."
"Callous." Twilight recognized the word Spike was struggling to form. "Bees rip their own organs out when they sting to defend their hives. What could be more callous than that?" And then the implication hit her. "Blowing themselves up of course!"
More infested ponies burst out of the ruined buildings and charged towards them. "We need to get a more defensible position! Fall back to base camp!" Twilight threw up a vertical shield wall to block the infested as they retreated from the city. One slipped through and got close to Pinkie Pie but she torched it with her flamers, then very improbably went flying from the explosion and landed in front of the fleeing company unharmed. "Oopsy daisy."
When they arrived back at the base camp the guardponies turned about and fired down on the approaching swarm. A few hits were sufficient to set the lot of them ablaze and the few survivors of the massive explosion were swiftly dealt with. Shouldering her rifle Applejack turned to her friend and princess, "so, do you have any sort of plan here?"
Twilight thought for a few moments, "okay, we've got an SCV, a barracks, and a small supply of mineral feedstock. We could probably construct a few of those bunkers I read about around camp and garrison our unarmored stallions in them. Anypony here think they could build around four steel plated bunkers?"
Applejack shrugged slightly, the bulging pauldrons over her shoulders exaggerating the movement. "I suppose, the number of barns I've had to raise just this past couple of years." She hit the release switch on her hardsuit and climbed out as it clamshelled open, then trotted over to the empty Space Construction Vehicle standing by the pegacoaches. As she clambered in she noticed that the interior was covered with levers and buttons and the heads up display was considerably more complicated than anything she had seen in the marine suit. "Uh, Twilight, do you have any idea what any of this means?"
Twilight sighed rather loudly, she knew it wasn't Applejack's fault, she probably knew the technology as well as any of the guardponies and herself was needed to fight. "You see a button with a post-it note marked "basic buildings" stuck next to it?"
"Hold on, yeah I got it." Applejack pressed the button and the HUD became filled with icons of Terran structures in miniature. "Whoa, nelly, that looks fancy."
"Okay, you see the building that looks like a dome on top of a short pedestal?"
"Like, half a ball on top of something else."
"Oh yeah, I can." Applejack pressed the first icon she saw that fit the description. A device popped off the back of her SCV and unfolded. "Now what?"
"That's the nanofabricator, I think you just need to feed some of the metal in the storage bay of the coach into it and it should do most of the work for you."
"Alright, I'm going, I'm going." Applejack retrieved a large ingot and placed it in the receptacle that appeared to be designed for it. Immediately the fabber's head started darting around the base of the building to be constructed, extruding molten metal and hardening it as it flowed to the ground. "Looks like this might take a while, are y'all sure we have time?"
Twilight considered the fabber's current pace and the horde gathering just outside the city. "Actually, no. We should have enough resources to fit some more of the guards with armor before you're done though." She went over to the barracks and opened the hatch, Fluttershy, still in her armor, and Rarity, still refusing to wear armor, were huddled towards the back of the room. "We're going to need this chamber soon. Can you get out and help?"
"There's monsters out there!" Both mares screamed at the top of their lungs.
Twilight shook out her mane as it was disheveled by the force of their yelling. "Listen, I can put you far from the front lines. Rarity, I think you could provide some telekinetic artillery or something."
"And what makes you think I could do that?" Rarity countered as she slowly stood back up.
"The slumber party, now just go." Rarity rushed out the hatch past Twilight as she started to address Fluttershy. "You say that you could hear the Zerg when nopony else could. We need you to tell us when they're going to attack."
Fluttershy just attempted to curl up even tighter than her hardsuit would allow. Twilight sighed heavily and decided she would have to pull the timid pegasus out the hard way, picking her up, suit and all, with her telekinesis and dropping her in front of the bunker Applejack was constructing. Or at least what she should have been constructing. As it was, the structure appeared to be far larger than what the schematics seemed to suggest, in fact the framework already laid down seemed reminiscent of a completely different building. "Applejack, I said a bunker, not a command center!"
Applejack's SCV was holding up a structural girder that wasn't fully hardened yet, the earth pony threw open the rear hatch and thrust her head out to reply, "You said to press the thing that looked like half a ball on top of something else. You didn't say anything about there being two things like that!" Meanwhile the fabricator's armatures continued to automatically weld armor plating to the superstructure.
"Well, it looks large enough to hold everypony bereft of armor." Rarity commented on the almost completed facility. "And correct me if I'm wrong but isn't that particular building needed to gather materials for manufacturing those hideous things you insist on wearing?"
"But there's no gunports for shooting out of." Twilight exclaimed. "Bunkers are supposed to have those."
One of the armored earth pony guards clumsily trotted up to the princess, "your highness, if I may." Twilight groaned and signaled for him to continue. "I could barely hold this gun straight without the armor, it kept bucking to the side when I fired. Once I put on the armor it was like my strength increased at least three-fold and I'm pretty sure that most of my shots went straight."
"So, you're saying that you need the armor in order to shoot?" He nodded affirmatively. "Very well, our first priority now is getting everypony in armor. Rarity, find some mineral-rich crystals, we didn't bring enough for the new plan."
At Twilight's command the camp sprang into action, the unarmored ponies filed into the command center once it was completed and ran out one by one to the barracks and received hardsuits. Once the Zerg attacked, a swarm of not only infested ponies but also conventional zerglings, Twilight directed her marines to concentrate fire on the infested, the explosions wiped out most of the swarm before it came even close to the base. However after the battle multiple marines complained that they had run out of ammunition, and the barracks was holding the most recently equipped guard. Twilight told Applejack to construct a supply depot, fortunately she knew what that was once Twilight referred to it as "those buildings the guards were receiving their ammunition and food from." Once the depot was completed the barracks' systems released the newly outfitted marine and the others grabbed more ammo clips from the counter. Unfortunately at that point their mineral stockpile was nearly depleted so Rarity pointed out some nearby deposits of gemstones and Applejack dug them up. It took several trips for AJ to gather enough minerals for a single marine so Twilight agreed to allow some other guards to pilot SCVs.
A second wave of Zerg attacked, this time zerglings surged forward alone. Gauss rifle slugs tore chunks and even entire limbs out of the predators, but they kept on coming despite their injuries. A small pack almost made it to Pinkie Pie but she incinerated them with her flamers, the beasts stumbling as their blazing skin cracked and their bones burst from the heat. Another pair of zerglings darted straight for the command center and began chewing into its armor plating before they were shot off by nearby marines. Twilight managed to levitate about half a dozen Zerg away from the marines they were tearing into, but still three of her ponies perished, their armor offering little more resistance than tissue paper to the Zerg's claws.
"There's too many of them!" One of the guards exclaimed as he blasted a rapacious Zerg off of his chest. Twilight had to agree, they just kept coming and this time there were no exploding ones to thin their numbers. They would have to retreat, any survivors left in Fillydelphia would be lost, and there was this odd screaming sound coming up from behind them.
An odd vehicle with a wedge-shaped nose and a pair of rockets on the back shrieked past the camp and around the Zerg horde. As it passed a series of small explosions, not as big as the ones produced by the infested ponies but still deadly, tore chunks out of several zerglings. The Vulture circled back and Twilight noticed a figure dressed completely in gray riding on its back.
The Vulture-riding mare flipped up her visor revealing a pair of red eyes and a rainbow-colored forelock half-concealing her cyan forehead. "Hey guys, looks like I showed up just in time!"
Everypony's reaction was immediate, "Rainbow Dash?!" Twilight ran over, somewhat awkwardly, to her pegasus friend. "I thought you were still in the hospital?"
Rainbow Dash seemed to shrug like it was no big deal, "I decided to check myself out early, before those hacks could cut off my other wing." Hearing the Zerg still snarling she turned her bike towards them and fired off another bunch of grenades.
"We can discuss it later." Twilight looked at Rainbow Dash's hovercycle, then at the Zerg swarm bearing down on them, and quickly came up with a plan. "We need to get some of those things off of us, there's too many for us to handle on our own. Try to draw them off."
Rainbow Dash flew straight through the center of the swarm, hovering just high enough to avoid most of the zerglings' claws. A number of them followed her as she raced away. But they could not keep pace and when she reached 50 meters ahead of them the Zerg turned back and rejoined the attacking swarm.
"Rainbow, they're turning back!" Twilight and her marines had managed to thin the attacker's numbers but as the zerglings that had followed the cycle-riding pegasus returned to the front line the swarm again got close enough to strike the defending ponies.
Rainbow Dash turned her head to look back at the Zerg she had been trying to lead away from her friends and saw them rushing towards them instead. "Hey, you're supposed to be going for me!" She dashed forward and stopped just as the rear line of Zerg got within grenade range, then fired. A zergling exploded then the one next to it leaped into the air and landed on the front of Rainbow's Vulture. In panic she fired the grenade launcher, the safety mechanism prevented it from detonating so close but the impact of what was essentially a 40 mm bullet still knocked the alien monster off, ripping off a square of hull plating in its blades as it went. Rainbow turned and sped away, though nowhere near full speed. This seemed to convince the Zerg to pursue her, six peeled off and ran after her, almost but not quite keeping pace with her this time.
Seeing the obvious distress her friend was in Twilight seemed to panic, drastically ordering her troops to "Take them out now!" and issuing a blast of telekinetic energy that threw the attackers back and caused no small amount of damage to them. Emboldened the marines were able to rip the Zerg swarm apart with another quick volley of gauss spikes, within seconds the battlefield seemed to be bare aside from several dead or dying Zerg and the still fleeing Rainbow Dash. When she noticed the guns had stopped she swung around and headed back for the camp.
But as she passed over a set of small craters disaster struck. The zerglings that had turned to follow her leapt out of the ground like great white sharks jumping out of the ocean and pounced on her hovercycle. She evaded most but two clung to her sides as she tried to kick them off, but they shrugged off her hooves and climbed towards her.
"No!" the Princess Twilight Sparkle lost concentration on the zerglings she held suspended and dropped them as she trotted forwards, dropping to all fours and running on the hardsuit's clenched fists. As the Zerg fell Pinkie Pie torched them with a quick burst from her flamers, pieces of barbecued xenomorph raining down as nearly everypony in the camp dashed after their friend and Princess. More zerglings popped out of the ground as they approached, attacking the distressed ponies.
Rainbow Dash stared at her friends falling into what was now quite clearly a deadly trap, then at the Zerg attacking her. "I don't think so." She pulled the throttle down all the way and channeled as much of her innate Pegasus gravity manipulation around the craft as her body could handle. The Vulture sped forwards in a multicolored blur, and then a loud boom was heard as she broke the sound barrier and the outline of a circular rainbow surrounded the site of the lowest sonic rainboom on record. The shockwave knocked the clinging zerglings off her bike and she ran into half the Zerg attacking the other ponies, sending them flying into the air. The ground was furrowed from the impact. With one side taken care of Twilight and her marines easily picked off the remaining disoriented Zerg.
As the least injured marines dispatched the few still living zerglings Pinkie Pie skipped around the smoldering corpses of the Zerg she'd fried. "They didn't go boom like those last ones?"
Twilight turned to look at the pink pony in the firebat suit oddly, then realized that she may have had a point and thought about it for a minute. "Considering we destroyed the last attack force completely by targeting the infested ponies it would make sense to not include them in the next assault. But we didn't allow any to report back, how would they know?"
"Maybe whoever Fluttershy heard commanding the Zerg before could hear and see what we did to them." Twilight was surprised to hear this suggestion coming from Applejack, who was busy repairing the damage to the command center. "That or they ran out of ponies to turn into exploding monsters, and considering that I have family in Fillydelphia I'd much rather that not be the case." As she was dumping solder on the long furrows in the building's armor she heard the local adjutant's voice in her commpiece, "not enough minerals." The soldering gun popped and gave out halfway down the gash she was working on, "I think we just ran out of metal."