As Applejack, Pinkie Pie and Zecora disappeared into the subterranean darkness, Twilight and Rarity were left to pace the edge of the chasm in thought. They weren't too worried about them - there was only just enough light to see by, from shafts of moonlight penetrating cracks in the ceiling and the occasional drain. Their attention was more on the problem at hand. The chasm ran perpendicular the street, extending into the distance, past insurmountable walls of rubble and collapsed building on each side of the ruined road.
"And you're sure you can't just wink us across? Is it really too much to ask?"
"I just don't think it's safe with how fatigued I am. It's been a really long day, and that last jump into the city really took it out of me..." Twilight sighed, and levitated a large brick over to sit on. Rarity, upon seeing this, tilted her head. She glanced at the gorge, and back at the rock.
"How about a more... direct approach?"
"What?"
"You lift me over the gap. And then yourself."
"I..." Twilight rubbed her head and yawned. "I suppose it's worth trying. After all, if I can hold up rocks..." With a wince, she picked up a small boulder and tossed it across, obliterating the remains of a wall on the other side. "Why not ponies?"
"I do hope you'll be just a tad more careful when that's me you're hurling around like a sack of potatoes."
"Of course..." Twilight stood up again, and braced herself near the edge. She gave herself a couple of slaps in the face to wake herself up, and readied her horn. "Ready when you are." Rarity nodded in acknowledgement, and jumped in place once or twice to warm up. She jogged back a few paces, before running to the edge at the fastest sprint she could manage. Once she was in the air, she felt Twilight's push giving her that little bit of extra lift, getting her as far as the edge of the other side. The impact knocked the wind from her lungs, and it was a desperate scramble to find a good hand hold. Hoofholds below were proving hard to find.
"Ngh! Twilight, a little help?"
"I'm... trying!" When Rarity got a glance back, Twilight was on her knees, visibly straining to hold her up. She could still feel the push, but it wasn't going to get her to safety by herself. And worse still, her handholds were crumbling; the old mortar, disturbed by the recent impact, was about as sturdy as oatmeal. Before long, her grip was gone, and the rock face slipped away. She wasn't falling as fast as she thought she should be; the extra lift was playing its role, but as her distance from Twilight grew, and acceleration built up, she could feel the wind starting to whip past her.
Falling from heights was becoming something of a habit of hers. Not to the point that she had a plan ready to deal with it at all times, but enough and recently enough that her first instinct wasn't to panic. It was almost as if, upon spotting a crevice or a ledge, some part of her expected to fall into it at some point. This, accompanied by her slowed descent, gave her the time she needed to put some of her own magic to work, and supplement Twilight's lift with her own. It wasn't as potent, and she hadn't believed her about the effect of fatigue on magic until she tried, but she tried to ignore it and ease her fall as best she could.
Thud.
She received another blow to her back, knocking her forward to land on her chest on the floor immediately after. She was in substantial pain, but she was fairly sure nothing was broken or severely cut. With a guttural groan, she turned to lie on her back and look up. It was still pretty dark up above, but surrounded by pitch black, it was her only reference point. She was too winded to call back up with any great effectiveness, but it didn't matter - Twilight was already on her way down. Sliding down the cliff face and hopping between surfaces with magic-assisted jumps, showing her state with a few sloppy landings and ultimately tumbling the last few lengths to the bottom, Twilight was at her side within moments of seeing her fall. She looked a little bruised herself, and the light spell she was trying to activate was dim and flickering.
"Rarity, are..." she panted, not even standing up properly as she crawled over. "Are you al..." She didn't even make it to the end of her sentence before she collapsed from exhaustion. Rarity wasn't sure if she'd fainted or not, but she figured she could do with the rest.
Hup. Applejack struggled on her landing, with Pinkie and Zecora having to help her up. Fortunately by now they were past the biggest gaps, and the way to the remains of the old palace looked fairly straightforward. The way behind them was criss-crossed with cracks in the earth, all of which they'd crossed at their narrowest point, making their route rather circuitous. The darkness had made their journey perilous - more often than not, their crossings were terrifyingly literal leaps of faith, simply guessing where they were going to land based on what they could see. So it was not without shaky relief that Applejack stumbled to her hooves and started towards the ruins ahead.
The blast hadn't been kind to the old palace; the bricks had been knocked aside like toy blocks, part of the level above had caved in, where a marble pillar from the Celestia-era palace had penetrated the roof. The only indication that this was even the same place was a set of black smears on the floor, in some shapes that Applejack and Pinkie only vaguely recognised. They picked their way through the devastation, turning over stones and poking at things, seeing if anything could be salvaged. What they remembered as the doorway was entirely caved in, and it seemed like nopony had been here since the incident at all. And why should they have? It was almost impossible to get here, and there would have been nothing to look for. By all accounts, everything in the old city should have been incinerated. It was a miracle the city wasn't blown off the side of the mountain entirely.
"How'dya reckon we get up?"
"This way!" Pinkie bounded at the wall nearest the hole in the ceiling and tried to grab an edge, succeeding only in throwing herself on a pile of rubble and scuffing her face. "Ouchies..."
"The route you suggest is indeed promising, but we will need a way to reach the ceiling."
Applejack gave it a mere moment's thought. Stairs were in short supply, but not the materials for a makeshift set. "Got some lights in that there stick? We could really use 'em if we're movin' rocks." The darkness masked the extent to which Zecora's eyebrow rose in response to the farmer pony's quip. Without even waiting for an answer, Applejack started feeling around the floor for rubble.
Fszh. A pale, flickering yellow light sprang into life. When she looked back around, Zecora held a small vial containing the source of the light, a meagre amount of yellow fluid. "An extract of the firefly's tail, properly disturbed, will light the way." Whatever you say, Mrs. fancy rhymes. "Now hurry, build the path up strong, the insects' light will not last long!"
Applejack wasted no time in piling some of the loose bricks and pieces of wall up into a small mound, not high enough to climb, but certainly high enough to use as a stepping stone for reaching the upper level. Pinkie tried to help too, but... well, it's the thought that counts. In reaching for her third brick (while Applejack was on her ninth), Pinkie put her hand on something slightly damp, kinda squishy, and definitely very icky.
"Ew! What is that?"
"What is it now, Pinkie?" Applejack rolled her eyes, set her brick down at the foot of the pile, and came to check out what had Pinkie so worked up.
"I put my hand in there and felt something icky-sticky!" Pinkie pointed at a crack, and looked for some other handholds to pull the rock free with.
"Pinkie Pie, now ain't the time to start freakin' out over... ah... oh mah stars." When the rock came free, a limp hoof, bloody, blackened and squashed out of shape dangled out. Without hesitation, the pair of them worked to pull the other rocks off of the hoof's owner. At the last one, uncovering her face, Applejack took a step back, removed her hat and held it to her chest. Pinkie chewed her knuckle, and even Zecora's inscrutable façade broke for a moment.
The body was barely recognisable; the face was mostly bare bone, and the coat was heavily charred and bloodstained, masking much of the pale midnight blue fur with a deep, earthy brown, matted with gangrene in places. The stomach was mostly gone, along with the viscera within, leaving a hollow blue shell with four legs attached. All four of them terminated in nubby hooves - this body had been here a while. Two wings hung from its back, at angles that looked like they'd be painful if this poor unfortunate still had the capacity for such sensation. The mane and tail had been tugged at and tussled, leaving them as messy mats, pressed against the stones below like the rest of her. Still, despite the ravages of time, Princess Luna's remains were unmistakeable.
None of them knew just where to begin - respects? Apologies? Should anything be said at all? Pinkie looked to Applejack. Hesitantly, she in turn looked to Zecora. The zebra raised her eyebrows and opened the hand on her shaft, keeping it in place with just the thumb, in the most minimal shrug she could manage. Unable to find words, Applejack just frowned, nodded at the body, and replaced her hat to get back to work. As far as she was concerned, it was a miracle it was in as good nick as it was, but they hadn't time to mourn her sacrifice now, and they certainly weren't properly equipped to move it to a safer place. To be fair, its current location was fairly safe - cold, dry, slightly slanted to drain any water that did find its way down here, and away from disturbance.
Before they left, with Zecora's light starting to fade away, Applejack deemed it fit to take few tiles that had fallen from the corridor above, and place them over the body. No sense leaving it in the open. Then, wordlessly, she carefully climbed the rock pile she'd built, and successfully grabbed the edge of the hole in the roof. With a helpful shove on her hooves, she was through, setting her up to pull her companions up.