It was the most commonly reoccuring symbol in the ancient book. As Rainbow Dash flipped from page to page, she saw it appearing several times—even more so than the symbols that she was familiar with. Sometimes, it would be the header of an entire chapter or paragraph of ancient words.
She was completely incapable of translating the text within, but she was nevertheless intrigued. This was likely due to the gratuitous amount of pictures that the book contained. She saw maps, complex diagrams of architecture, engravings of mountains and wilderness, and more than a trough full of cryptic imagery.
Other than the one reoccuring crest, Rainbow Dash saw something that struck her funny. Even though she couldn't interpret the words or the many symbols surrounding them, there was something uniquely familiar about the hoofwriting. She could have sworn she had seen such similar brusthstrokes when being forced in grade school to skim over the old manuscripts covering Commander Hurricane and the founding of Cloudsdale. A motif feathers and marble architecture in various illustrations only further supported this.
"Was this thing... written by pegasi?" Rainbow Dash murmured aloud.
In the glow of crystals, she gazed aside at the winged skeleton. She saw what looked like the tattered remains of a robe lying a meter away from the pony bones. Reaching over, she turned the fabric around until the hood of the article graced the cave air. On the tip of the hood—above where the equine's face would have been obscured—was the same crest as that which was filling the book in her hooves.
"Looks like you had dedicated your life to something, pal," Rainbow Dash muttered. "You think it was worth it?"
Silence resumed, save for the flipping of pages as Rainbow Dash tore deeper and deeper into the tome. She slowed as she saw hauntingly familiar things. Towards the middle of the book, there were several detailed diagrams of gears, pendulums, conveyor belts, and pistons. She knew that she had seen all of these things before.
"How did these dudes see it?"
She flipped some more pages. The glow around her was intensifying. She found an illustration towards the end of the tome that occupied two sheets. Before her eyes, a majestic series of marble steps and concrete platforms extended into an unfathomably large waterfall stretched before infinite starlight. A grandiose palace bravely stood against the face of oblivion.
"The edge of the world..."
The cave was as bright as daylight at this point. A wind was picking up as the place echoed with a deep, bass resonance. Just as a shadow began creeping over Rainbow Dash—
She slapped the book shut, spun around, and smirked. "Ah ha!" She pointed at an immense shadow peering over the edge of the plateau of gemstones. "Thought you had me, huh?! I've been in too many caves to think that they're completely empty!"
A bulbous red shape leered at the stony edge of the platform. Two long, crimson feelers waved in the glowing air.
Rainbow Dash grinned. "What? You shy or something? It'll take more than that to scare me—"
A gust of musky air blew at Rainbow Dash, followed by a shrill shriek as the creature's head lunged up into the space of the cavern, followed by a pair of legs, then followed by another pair of legs... then another... and another... and another...
Soon, half the body of a one-hundred meter long giant centipede was thrashing before her, waving all of its legs as its headpiece curled about, looming directly over her.
Rainbow Dash had fallen on her flank at this point. She scooted backwards until her spine was to the wall. "Well then..." She gulped. "That's a start."
Another gust of air emanated from the giant arthropod's interior. At the front of its headpiece, a pair of feelers slimily unrolled to reveal twin bards of poison, beneath which was a razor-sharp array of hungry mandibles. The dagger-sharp stingers extended an extra foot each, and the massive thing lunged at the pony.
"Nnngh!" Rainbow dove out of the way.
The ground behind her splashed with gemos and the brittle remains of pegasus bones.
Rainbow scrambled over the shaking plateau. She had to hop over the dragging body of the centipeder—her tail hairs getting briefly caught in the monster's squirming limbs. She broke free, scooped up the book with one forelimb, scooped up a clump of glowing blue rods in the other, and took off for the ascending tunnel above.
The centipede at this time had recoiled its upper body and was lunging at her yet again.
The monster missed by a hair, smashing into the mouth of the gem-encrusted tunnel, showering red rubies down into the throat of the impossibly deep cavern.
Rainbow Dash easily outflew its attack. Once she was several meters above it, she perched on an outcropping of rock, placed her items down, and spun about.
"Okay, you barf-flavored bucket of crab legs!" Rainbow Dash sneered with a wicked grin as she grinded her hoof on the cliff of rock. "You wanna do this the hard way, bucko?! I'm gonna make you wish you had a hundred crutches after I'm done with—"
She froze in place. Her ears drooped.
The creature was thrashing and shrieking angrily below her. It was disoriented in its furious hunger. Rainbow could have pounced on it at anytime.
Instead, she stood up straight and turned around, gazing straight up towards the small speck of sunlight.
Rainbow Dash gulped. After a deep breath, her features softened, and when she looked down at the creature once again, it was with a tiny smile.
"You know what? As much as I'd love to do the dance of the million feelers, you're just not worth my time."
She scooped up the book and crystal rods yet again. Her wings flapped.
"Consider yourself lucky, lame-o."
She shot up, ascending towards the distant entrance of the cave.
The monster was not about to let the whole thing slide. Once it had gathered its bearings, the massive centipede gripped the walls of the cave in its countless limbs and clambored up after her. Its furious shriek filled the claustrophobic chamber as its rancid breath blew at Rainbow Dash's tail hairs.
There was no way Rainbow couldn't have felt it.
"Belle! Pilate!" she shouted as she sailed like a blue blur towards the tunnel entrance. "Now would be a very good time to call off this picnic and gallop away!"