Everypony reacted at once and with amazing coordination. Luna leaped straight up toward the ceiling to dodge the leaping Nightmare while Celestia and Twilight both shot quick bolts of light magic at it, causing it to stop and shrink into itself with apparent pain, and then Ash pounced on top of it, literally breathing the sparkling night-dark aura in as he passed through it. He hit the ground and remained motionless for several seconds, and then black splotches started appearing on his coat, his mane and tail both started twitching wildly, and he began screaming while holding his mouth firmly shut with both front legs. Luna quickly landed, and she, Celestia, and Twilight all gathered around Ash with their horns aglow but unsure whether to act or not. The black splotches grew until roughly half of Ash's coat was recolored, and then the muffled screams stopped and his eyes opened. One eye was the normal vivid green, but the other was teal and had a vertically slit pupil.
"Ash?" Twilight asked, hesitantly hopeful but fearing the worst. The unicorn's mismatched eyes flicked over to her for a second, but then focused on Luna as he got back to his feet.
"Don't you want me back, Luna?" he asked, his plaintive voice pitched in a barely recognizable imitation of Nightmare Moon. "Wasn't I a part of you? Some of your power still resides in me, forcibly removed by this… creature forcing me to speak to you through him. You must miss it."
"I've had more than enough time to regain that power on my own," Luna said. "Nor do I miss the whispers of petty jealousy and discontent. Begone, Nightmare; release Ashen Blaze and fade into obscurity. You will find no welcoming home, let alone a kingdom, in any land where my moon watches over the night."
The Nightmare stood in motionless silence for a moment, and then lowered its eyes with a scornful chuckle. "Even if I believed you," she said, "Ashen Blaze is refusing to let me go. He's 'lending' me his body and energy, but refuses to let our minds become as one. If his will were just a little weaker, I'd-" Its head jerked back suddenly, and for a brief moment the teal eye returned to Ash's normal green, but then it changed back and the Nightmare grumbled angrily, "Aggravating stallion."
"What were you doing controlling that Changeling?" Twilight asked, pointing to the unmoving insectoid pony by the window.
"Surviving, barely," the Nightmare said dryly as it looked at the Changeling. It then looked at the broken window and cast a spell that covered it with an opaque black barrier. "I'm honestly surprised they haven't all tried coming in through the windows," it said in an aside. "Changelings make terrible vessels for me," it said, looking back at the alicorns. "The whole race is starving and yet they all trust and obey Queen Chrysalis to the extent that they have almost no personal ambition to sustain me. I was going to take Chrysalis herself, or die trying, but someone else got to her first. A large creature, garishly colored." It paused for a moment as if distracted by a passing thought. "Ash suspects it answers to the name of Vanatos, a monster from another universe somewhat like Tau'rin, and yet not."
"That stone lodged in Chrsyalis's leg!" Twilight exclaimed. "Vanatos must have done what he tried to do with Discord and the Topaz: give her a Chaotic Gem in exchange for a promise to use it for revenge. Everything about this invasion is simply oozing with Dark elemental magic. Although, that stone didn't look like an amethyst…"
"I gather you witnessed this exchange, Nightmare," Celestia said stoically. "I'm curious why that would have prevented you from attempting to possess the Changeling Queen anyway. The element of Darkness would suit you well."
"Oh, I was tempted," the Nightmare said, rolling her eyes. "But you see, this invasion's been in the works for a couple of days, and in that time I saw enough to convince me that I want nothing to do with the power Chrysalis has now. Call it an attack of conscience."
"Why though?" Luna asked. "What has Chrysalis done that would appall even you?"
"Don't you dare look down on me, Luna," the Nightmare said. "Deny me all you want, but we were one and the same once. Do you even remember our purpose for existing together? Attention, respect for the night, appreciation. For that, you need subjects; living, breathing, free-thinking ponies to serve and worship you."
"Until your eternal night destroys their crops and freezes them to death," Twilight deadpanned.
"Would you let me finish, filly?" the Nightmare snapped.
"I will once you stop trying to justify yourself and get to the point," Twilight countered.
The Nightmare glowered at Twilight, and then rolled her eyes again. "The dark power of the Gem Chrysalis received has altered the Changelings so drastically that they're now little better than constructions of pure magical energy. I don't know if Chrysalis is aware of this, but most of her army isn't even real anymore."
"I'd say it's real enough," Twilight said. "Whatever the case is," she continued, starting pace as she entered lecture mode, "our best bet is to re-gather the Elements of Harmony before taking the fight to Chrysalis and getting the Gem of Darkness away from her. The problem is, I have no idea where everypony ended up, and there may be more of those hulking, magic-reflecting Changelings around. I don't know if we can even hold out long enough to find everypony."
The Nightmare started to laugh, a low chuckle at first as it looked down at the ground, and then it started to rise in pitch and volume. Before the sound could reach the level of a full-voiced, evil laugh it was cut short with a strangled hitch of breath and the darkness rapidly flowed off Ash's body and gathered into a sparkling cloud contained within an orange glow of magic just above the tip of Ash's horn.
"Ok, I've had enough of the evil ham routine," Ash said. "Not that I don't approve of savoring the moment, but is not the time or place, Noctus." The Nightmare aura writhed insolently within the unicorn's magic, but he seemed unimpressed.
"What was so funny?" Luna asked.
"To make it short," Ash answered, "Noctus here could move through Chrysalis's artificial darkness undetected and very quickly. Assuming all the Element Bearers, and my team, are in Canterlot, she could find them all within minutes. By herself, however, she wouldn't be able to transport any of them to us, and I don't know if she'd even last very long without a willing host."
"You're suggesting one of us must submit to the Nightmare," Celestia said.
"I'm volunteering," Ash responded. "She wants Luna, but of course that's not going to happen. No offense to you or Twilight, Princess, but I don't think either of you could keep ahold of your own minds under her power. I'm the only dependable option."
"Is the risk really any less for you, Ashen Blaze?" Celestia asked pointedly.
"After the last few minutes, do you honestly doubt me?" Ash countered.
Celestia paused in thought, and then smiled serenely. "I suppose if anyone can master the Nightmare, it would be the pony who removed it from Luna in the first place."
Twilight grabbed Ash in a tight hug, being careful not to touch Noctus, and whispered, "I trust your judgment, but be careful, ok?"
"You have my word," Ash said. Satisfied, for Ash's word was as binding as a Pinkie Pie Promise, Twilight stepped back and let him proceed with pulling Noctus back into himself. For a moment, nothing seemed to happen, but then suddenly Ash's body underwent a transformation even more dramatic than the previous possession. The starry aura of the nightmare surrounded him as he grew to match Twilight's stature, his horn elongated slightly, and a pair of midnight-black wings appeared on his sides. His coat took on the same midnight black color, his eyes shifted to the Nightmare's distinctive teal draconic shape, and his mane and tail were transfigured into billowing smoke laced with red embers, and glowing like fire at the roots. Even his magic-enhancing necklace underwent a transformation into a single, solid collar of fused gemstones with the symbol of Meis Thamule engraved in the large, central ruby section and filled in with gold. Only his cutie mark remained unchanged. "I'd find a good location to lure Chrysalis to for the showdown, if I were you," he said to the Princesses, his voice sounding a bit more grandiose but still uniquely his own. "Somewhere defensible too; this may require multiple trips, but I'll be as quick as possible. Stay alive." With that, he turned into a dark mist and flew out of the room through the window.
"Was that Ash talking, or the Nightmare?" Twilight wondered aloud.
"A little of both, I would say," Luna said. The door shuddered as something outside began pounding on it like a battering ram. "I think it's time we left," Luna said. "I recommend the Night Tower; it should be easy for three of us to hold against the enemy."
"Anywhere's better than here," Twilight said as a large Changeling hoof burst through the door. The three alicorns teleported as one, and by the time the Changelings finished battering the door open and poured into the room, there was no sign it had ever been occupied.
The being that was Ashen Blaze, Noctus, and both at once flew silently and invisibly through the artificial night engulfing Canterlot, appearing outwardly as nothing more than wisps of dark smoke nearly impossible to discern against the shadows. The battle between the Dark Changelings and the city's defenders was now fully engaged, and except around the pink dome covering Discord's area the Changelings seemed to be pushing the Royal Guard back toward the castle on every side. Ash/Noctus flitted about, going from one pocket of fighting to the next, ignoring the urge to materialize with dramatic flair and beat Changelings back. Ash's iron will and pragmatism kept them on task, despite Noctus's tempting whispers.
Technically they were of one mind now due to the extent Ash had allowed Noctus to meld her essence with his, but the stream of their background thoughts as they searched the city resembled a dialogue more than anything else.
This is something I could get used to.
I have to remember it's only temporary though; that was the agreement.
That doesn't discount future arrangements. This form deserves a name of its own.
Nothing with 'Nightmare' in it though, assuming…
Maybe something derived from the origin of Noctus then? Noctu-
Is that my ship?!
Sure enough, through the distant haze of darkness Ash could see the Lirin flying about erratically in an attempt to dislodge the Changelings that clung to it like barnacles. Barnacles with deadly sharp teeth, as one bit into a section of the ship's hull and tore it open as Ash approached. Rage filled Ash's mind at the sight of his property being damaged, and in a blink he was in the midst of the Changelings and materialized in a burst of flames. One Changeling, a mere construct of the darkness, disintegrated outright and two others were blown away and lost to sight. The remainder paused to look at the smoldering newcomer, and that lapse of activity proved to be their downfall. "Get. Off. My. Ship!" Ash cried, punctuating each word with a magical blow that sent multiple Changelings flying until the ship was clear of them. Satisfied but still angry, Ash gave the Lirin a quick look-over. The hull was torn open in several spots, but the wings looked sturdy and the ship as still flying, so Ash teleported inside to take PC to task for blatant violation of orders and common sense. He only had enough time after materializing in the main cabin to draw in a deep breath before Applejack bucked him in the side of the head, which sent him flying into the wall.
"Take that, ya no-good Changeling," AJ said with a snort.
"Easy Applejack," Ash said, ignoring the ringing in his ears. "It's me, Ashen Blaze."
"Ash?" AJ exclaimed. "What in the haycorn happened to you?"
"Long story," Ash answered, standing up and getting his wings settled right. "What the skeb are you doing on the Lirin?"
"I never got off," the earth pony answered. "When Twilight's spell went off, it just used up all the Magebane I was carryin' fer Gale. I talked PC into trying to get me to the castle or wherever the rest of y'all wound up. I'm kinda regrettin' that now."
"PC," Ash prompted.
"Voice print recognized as Ash," the computer said. "Reestablishing standard command protocols. That new look of yours befits Meis Thamule more than Ash the Pragmagic, sirrah."
"No argument there," Ash said, looking himself over. "What's the damage?"
"Multiple breaches to the outer hull, one engine has been taken offline for safety, and internal systems are suffering several minor glitches due to magical interference. My own hardware is undamaged. Flight is still possible, but interdimensional travel is not recommended at this time."
"Skvetch," Ash swore loudly, and then brought his/Noctus's frustration under control. "One disaster at a time," he said. "One moment." He returned to the exterior of the ship and, after discouraging some Changelings from taking an interest in it, tapped Noctus's power to wrap the Lirin in a shield that would hide it from sight and protect it from further damage. Going back inside, he instructed, "PC, head for the castle and land as close to where Twilight and Princesses are. Remain there unless the Lirin is in danger of destruction. Get the skeb out of town if that happens."
"Despite how recent events may appear, I do know how to protect the Lirin, sirrah."
"Just don't you dare fail me," Ash said, and then he was gone like smoke in the wind.
"That's just downright creepy," Applejack said to herself.
Ash and Noctus found Rarity and Fluttershy in the gardens, utilizing three transplanted hedges, four particularly thorny rose bushes, and a tree with wide-spreading branches and thick foliage as an improvised fort guarding what would otherwise have been an easy way inside the castle through the event hall. Fluttershy had managed to coax the toughest and bravest of the garden's animals into fighting, and so the Changelings trying to get through found themselves constantly bombarded with nuts and rocks thrown from the tree, swarmed by birds of all shapes and sizes, and rendered blind and confused by spells of light and illusion thrown out by Rarity. Over it all, Philomena harassed a few Changelings that tried to come in from above. One Changeling got lucky and smashed the pheonix's ribs in, but paid for it when Philomena grabbed its horn with her last breath, so that she was lying across its eyes when she burst into flames to regenerate.
Ash landed with a flourish of magic that cleared the area immediately around the improvised fort of Changelings, and then struck a pose that put him in profile.
"My word," Rarity said, flustered by the display and recognizing the black pony's cutie mark. "That was quite an impressive entrance, darling."
"Thank you," Ash said magnanimously. "You seem to be doing decent work here ladies, but I'm afraid I must take you away from it. Duty, and Twilight, calls."
"Oh, of course," Rarity said, leaping daintily over the hedges and trotting over to Ash. "By all means, take us to her."
"Wait," Fluttershy said. "Just for a second, if you don't mind." She went over to the pile of phoenix ashes just as Philomena rose out of them. "Philomena," Fluttershy asked, "do you think you and the garden animals can handle things on your own?" Philomena let out a low, derisive squawk and gave Fluttershy a mildly insulted look. "I'll leave you to it then," Fluttershy said with confident pride, nuzzled the phoenix, and then finally joined Ash and Rarity.
"Things might get a little smoky," Ash said, "but don't panic. It'll pass quickly and smoothly. I think."
Locating the Spiriter twins was a matter of finding the signs of their passage. Despite the all-encompassing darkness and shifting tides of battle, the power of Heart and Soul's spirits focused on removing any obstacle standing between them left a mark that stood out to Ash's Noctus-enhanced eyes. The Dark Changelings seemed to sense it too, because when Ash finally found the midpoint of the line between Discord's dome and Heart's point of entry into Canterlot, he found the twins and Pinkie Pie surrounded by dozens of the creatures, and more were visibly growing from the shadows to join the fight. Heart, Soul, and Pinkie were each doing the three pony races proud, holding the tide at bay with whirling Element Wheels, whipcracks of spirit tendrils, and a party cannon. Ash was entranced by how smoothly Pinkie had integrated into the almost dance-like movements of Heart and Soul fighting at their peak of unity, but then the Noctus part of his mind reminded him of their task, and he landed in the midst of them.
"Excuse us," he said apologetically to a random Changeling, grabbing the trio in his magic and teleporting away in a puff of smoke.
They reappeared on the upper viewing platform, ordinarily used by ponies wishing to watch Celestia and Luna exchange their duties at dawn and dusk. The Lirin was now parked there under its protective veil, which Twilight and Luna had adapted and spread over most of the platform to cover the ponies Ash had gathered. The Princesses's original plan to take and hold the Night Tower had been rejected due to space considerations. As soon as he regained his bearings, Soul turned to look at Ash and raised an eyebrow at his friend's altered appearance. "I see you've made a devil's deal," he said dryly. "The straits must be dire indeed."
"It's a temporary arrangement, believe me," Ash answered. He took a quick count of the ponies on the platform, and then faded away with the words, "One element to go."
Heart and Soul exchanged a look, and then the golden-yellow unicorn grinned at everypony else and asked, "So, how's everyone else's day been so far?"
"Are you sure you're still with us, Rainbow?" Gale asked between shots.
"Would you quit asking me that?" Rainbow Dash asked angrily, kicking a Dark Changeling in the face and barely flinching as it evaporated into shadows. "I've faced Nightmare Moon and Discord twice each, an angry gang of griffons, Tau'rin, Z'Nai-possessed ponies, all sorts of monsters from the Everfree Forest, King Sombra, and the possibility that the Elements of Harmony accidently vaporized Twilight. I can deal with these Changelings popping like balloons."
"I think you've forgotten about getting thrown through the space between universes and turned into a human. Or was that not actually traumatic for you?" Gale, Dash, and several guards looked up smartly to see a black alicorn with ember-laden smoke for a mane and tail and a multi-colored gem torc coming in for a landing among them. Not sure what to make of him, they all trained their weapons on him. "Steady folks," Ash said placatingly. "Don't embarrass yourselves." Gale narrowed her eyes, glancing between Ash's face and the gold-leaf sigil engraved on his torc, and then very slowly gripped the gel launcher trigger in her mouth. "Gale, just don't," Ash said in a hard tone of voice. "I've had a very good time of gathering our scattered forces, and you're the last two. Don't screw this up for me at the last minute."
"Fine," Gale said, releasing the trigger, "but we're going to have words after this is over."
"Did the darkness get to you or something, Ash?" Rainbow Dash asked, eyeing the black pony's wings dubiously.
"Or something," Ash replied. "Proper explanations can wait. Sirs," he said to the guardsponies, "carry on." Without waiting for a response, he vanished, taking Gale and Rainbow with him. The guardsponies looked at the vacated space for a moment, and then back out at the Changelings moving to surround them.
"I always figured he was of the type to take everypony out of situations like this," one of the lower-ranked stallions said.
"Cut the chatter," the seargent snapped, burying his own disappointment beneath years of training and then taking his frustration out on the first Changeling to come within point-blank range of his Gel Launcher.