Twilight held a large branch in her mouth, nudging her way through the thick brush and scrub that stood in her way.  She hacked away at whatever wouldn't move with a push, and slowly picked her way into the heart of the Everfree Forest, not daring to use her magic.  Every single ounce of pain that had settled into her body from the constant assault of cuts and bruises had faded and taken up residence within her mind; she felt as though her brain would explode any moment.  With a few deep breaths, though, she pushed onward, never really hoping for anything more than an end to this state of perpetual discomfort.  She performed her actions like a robot: methodically moving forward, hacking away at brambles with her improvised weapon, stalling to clear away the thorns, and then moving again.  

After what felt to her like an eternity, Twilight emerged into a clearing where the trees seemed to arch and web over each other.  Twilight could see no sky, nor leaves even, but only the twisted bark of tree trunks reaching into the air and weaving together into a dome above her.  The area was a near perfect hemisphere, and at the center sat a perfectly circular pool of luminescent water that cast a beautiful blue glow onto the entire clearing and the instant Twilight stepped inside, she could feel a very strong magical force wash over her.  The feeling was absolutely invigorating, and Twilight felt a deep shudder hit her spine as the pleasurable feeling surrounded her being and warmed her from the damp cold of the forest.  

She moved in toward the pool, throwing caution to the wind and simply wanting to see her reward first-hand, which did not disappoint her.  The water that came from the spring had a glassy finish to it and what seemed to be a very low surface tension.  The surface of the fluid rippled as she approached, picking up the slightest vibrations even in the ground around the spring.  She couldn't see into the pool, receiving only a perfect, rippling reflection of herself staring back with one change.  Something about her eyes wasn't quite right; they didn't really look like a set of normal pony eyes, instead seeming to be all dark-purple with a barely noticeable pale violet in the center.  She figured this was just some trick of the pool, though, and didn't pay too much attention to them.  

Twilight reached her hoof down and touched the liquid, feeling almost no resistance from it as her foreleg sank into the depths.  Everywhere on her skin that the water touched felt like an electric current was running through it, invigorating the nerves and muscles in her body and warming them, but never to the point of discomfort.  As a matter of fact, Twilight had never felt anything quite so amazing in her life, and had to fight herself from simply diving into the pool.  In a small fit of desperation, Twilight turned to read from her book, seeing nothing in the pages and asking what exactly she was supposed to do with the fluid here.  

"As I've said before, you have to evaporate the water and collect the salts from it.  Simply take what you need, though, for it is somewhat dangerous to take too much from this place."

"What'll happen if I take too much?"

"I'm unsure, though I have a feeling the forest will destabilize.  All things considered, this pool could be the font of magical energy for every plant in the Everfree, so we don't want to disturb it too much more than we need to, lest it destroy the ecosystem.  However... Toward the end of my life I was doing some research on the properties of the salts in here.  That research I will share with you after our little ritual."

"Well...  How much did you say we needed?"

"Just a few hoof-fulls for you.  The crystals will be very large, so get as many as you can.  I'm sure just one or two gallons of the water will suffice, but take what you need until you feel comfortable in the amounts."

Twilight set the book down on the grass around the pool, glancing around to ensure her safety and then setting to work on the pool before her.  She tried her water magic to lift the fluid out and examine it, cautiously at first in anticipation for the upcoming migraine, so only taking a few drops up out of the water.  The pain never came to her, however, so she pulled a much larger volume out of the pool and hovered it in front of her eyes.  Twilight took a few steps back, levitating the shimmering mass of water just a few inches out from her face and examining it.  Still, she could not see through it; it was completely opaque and perfectly reflective, though seemed to have no viscosity.  She heated the sphere by simply applying energy into it, watching small bubbles break on the surface of the fluid and becoming almost captivated by it.  As the ball of mercurial water slowly began to decrease in size, a large, perfectly white crystalline shard fell out of the bottom and plummeted toward the ground.

Twilight caught the thing with her telekinesis before it impacted the forest floor and brought it over to her, keeping her ball boiling and floating in the air while simultaneously examining the crystal.  Unlike the water, the substance was almost as clear as glass, but the visible portions of it retained a perfect white that could rival fresh morning snow.  Out of the corner of her eye, she could see another of these crystals fall out of the ball, but this time she couldn't quite react to it and it hit the ground.  The fragile-looking thing was deceptive in its looks, driving itself into the ground about halfway without any bouncing or adjustment of position; Twilight concluded that the substance, whatever it was, must be very dense.  

Twilight allowed the water to boil away completely, taking at least two hours (though she superheated it toward the end to try and speed the process) and collected each crystal as it fell.  She left the one on the ground to see if it had any kind of change, but couldn't quite observe anything different about it.  After a quick consultation with Iago, she determined that it would be best to just leave it there lest it taint the batch that she was going to use.  Once the last ounce of fluid formed itself into a large, identical crystal and faded away, Twilight examined her collection.  It seemed that each one was completely uniform with each other, forming an asymmetrical shape that somehow managed to stay exact amongst all of the crystals.  She decided that if any were left after the ritual she'd need to study everything about them.

After realizing that she had forgotten her saddle bags for this trip, Twilight set her torn cloak down on the ground, flattening it out and examining it for a large enough, contiguous space to set down the tome and the crystals if she could.  Luckily for her, she moved the tome in the open position down onto the cloth before the crystals and spotted the most recent entry: "Don't put those salts down!"

Twilight complied with the demand and kept them levitating, examining the book for what Iago wanted her to do with them.  

"I'm rather glad you didn't bring your saddle bags for this, because I would not allow you to place those valuable things in them anyway.  These crystals can't touch anything, as a matter of fact even air can degrade their quality.  I want you to turn the page and place the entire pile down, then close this book.  Can you do that for me?"

Without answering, Twilight simply turned the page and gently laid the crystals as balanced as she could onto the blank paper, closing the tome with her telekinesis and worrying that she would crush the salts or shred the book.  Without any noise at all, the book closed just as if she had closed it any other way, leaving no space or bulge to worry about, and no crystals to be found.  She flipped the tome back open and examined the glowing script that sat anew on the page.

"I'll keep these safe until you need them.  Thank you, Twilight Sparkle."

"Hey, that's pretty nifty...  How'd you do that?"

"It's just a simple void conjuration.  I can teach it to you after you've performed the ritual, but I'm afraid it would be too impractical and tedious to do it through this bothersome script.  I dare say you've gotten plenty of these for now, so I'd suggest you leave the forest before nightfall comes."

"Just one thing, first.  I'll be right back."  Twilight didn't even wait for Iago to respond and simply closed him up on her cloak, leaving him in the grass and stepping over to the pool.  She spotted the crystal that she had dropped and examined it in the ground.  The grass and other vegetation immediately surrounding the embedded shard had grown up around it and sprouted toward the sky in that short time.  Twilight figured that something about these crystals changed the fertility of the soil around them, and decided that a future study into the properties of these would definitely be in order.  The unicorn then moved onto the actual spring, deciding to smell the air directly above the pool of shimmering liquid and picking up a fantastic scent that she had never experienced before.  It seemed to her to be every single delicious smell in the world merged into one; infinitely pleasing, but not overpowering, and yet giving Twilight no one way to describe it.  She could no longer stop herself and dipped her nose into the water, gulping back several mouthfuls of it before coming up for air.  

The liquid gave the sensation of a very fine aged liquor; burning her throat on the way down, but not harsh enough to be displeasing.  It tasted kind of like flavored water, but she couldn't quite pin down the flavor, much like the smell of the fluid itself.  To her, it tasted like everything she'd ever tasted in her life, and she quivered in excitement from the wonderful feeling within her.  Everything seemed to be teeming with energy in her body; her nerves were all excited at once, and her senses were sharpened until she could locate the exact distance of a butterfly off in the distance simply by listening to the flapping of its wings.  She stumbled back to her cloak and book, flipping it open with her telekinesis (or rather slamming it, the power behind the action had taken a mighty leap forward).  As she began to explain the feeling, she was interrupted by frantically scribbled glowing text on the page.

"Foolish child!  Please tell me you didn't drink from the pool!"

"Huh?  What's the big deal Iago?  That water is... incredible."

"It's 'incredible' because it's pure magic.  Do you understand what that much power in your body could do to you?  Have you ever seen a tree get struck by lightning?  Or a moth fly into the flame of a candle?  How much did you drink?!"

"Just a few mouthfuls...  I'll be alright, won't I?"

"A few mouthfuls?!  Great... The most promisingly venerable student I've ever had was silly enough to actually drink the water.  No other pony will ever find me in this part of the Everfree..."

"Wait, what?!  But I feel just fine.  Maybe a little warm but..."

"You have five minutes or so before you'll feel the full effects.  It does have to enter your bloodstream you know.  Might as well say a few last words with the time that you have left...  I suppose you'll at least go out in an interesting way."

"You mean I'm going to die?!"

"I'd say you have an eighty percent chance of immediate death, fifteen percent chance of severe tissue damage and then later death, and a five percent chance of survival.  To put it bluntly, you'll probably burst into magical fire if you can't release enough of that energy.  The fire that this causes in organisms is beautiful though...  Have you ever seen a flame that burns pure black?" Iago's coldness toward his student's endangered life brought the situation into perspective for her: something very, very bad was about to happen, and the feelings in her stomach were definitely attributing that to fact.

Twilight panicked, moving aside and kneeling onto the ground.  She could feel her stomach growing more and more warm from the fluid inside of it, so she quickly pushed her hoof into her mouth, trying to induce her gag reflex.  It worked; the unicorn vomited up what amounted to mostly silvery liquid that burned her throat and tongue as it exited, but she could still feel the building energy in her system.  Every one of her nerves was tingling with that same energizing feeling that had washed into her skin the instant she stepped into this dome, though it continued to grow until it was actually painful.  She levitated herself, getting off of the ground and looking around her surroundings for some kind of solution, though she wasn't quite sure what she was going to look for.  She saw an errant tree attempting to grow within the clearing, so she tried to light it on fire, figuring that she could simply push the magical energy out of her body by practicing her elemental magics (fire being the most intensive consumer) but was reminded brutally of the magic ward within this portion of forest by a splitting headache.  

The unicorn glanced around frantically, trying to find something to burn and some way to get this power channeling before it destroyed her body, eventually looking down and seeing her own two hooves.  She grimaced, but resolved to put up another form-fitting barrier on her body and, experimentally, light that barrier aflame.  Her hooves, already shimmering with a magical shield, lit with a roaring fire that extended up to her elbows, causing her to blink rapidly and forcing her to focus on several things at once.  She could feel the building energy slow down, but not quite stop in its progression, so she resolved that a slightly more intense version this self-conflagration would be the only way to survive.  Floating there above the magical pool, Twilight lit her entire body, magically shielded, into a roaring inferno that put the brightness of the glowing spring beneath her to shame.

Twilight could open her eyes without fear of them drying out thanks to the shield, but she could literally see the bases of flames rising from her pupils, sending bright light directly into her retinas.  She kept her eyes clenched shut and tried to monitor her panicked breathing; every single lungful of air she took was far too hot to be comfortable.  She could feel the power in her body being pushed through her and expunged into the fire around her body, so she knew this was the only way to go, but it was still a horrifying thought.  If she let her barrier fall, she'd be incinerated at the heart of this conflagration, and if she let herself fall then she'd hit the magically guarded floor and probably have her mind assaulted once more.  If she let the flames fall, the magical water in her body could annihilate her very being, so her life literally relied on her focusing on each of the three events without fault, lest she be consumed in a very painful way.  She kept everything consistent, but still felt the power rise within her, so she upped the 'fuel' to her inferno, bringing it into a massive cinder that rose up nearly twenty feet away from the unicorn's levitating body.

She curled herself into a ball, floating in her fiery prison, trying to expend every ounce of extra energy that she had taken in, forcing it out of her body through mighty flame that could intimidate even the bravest of dragons.  She felt her muscles twitch and her nerves tingle: the fire wasn't enough, but she couldn't apply too many of her mental faculties to it lest she lose focus on her levitation or barrier, so she resolved to simply fly up.  The sound of flames whipping as the air above her flowed around her frame buffeted her hearing until she was nearly deaf, but she managed to use the white noise as a way to help keep focus.  She knew she'd hit the ceiling eventually, but couldn't think of anything else to do without killing herself, and so braced for both the mental and physical impact.

The magical fire around her body was so hot that the trees above her were immediately consumed upon her getting close to them, and although her mind was wracked with pain, she kept her upward path right through the canopy.  The dome was no match for her, and the ward shattered at the might of her magical exertion, sending her bursting forth from the forest and sailing into the sky.  Her body left a trail of flames nearly fifty feet long as she continued up into the air, body aflame with the most intense fires that anypony would ever see, though she was just far enough out of sight from any livable area that nopony actually did.  Her barrier held strong, and the flames continued to burn away the excess, leaving her just enough leeway to manipulate the area of the fire around her as she sailed into the afternoon sky.  She removed the fire from her head, allowing her to breathe fresh and cool air as long as she moved forward, as well as to see where she was coming from and where she was headed.  

She looked down in a bewilderment, watching her fiery form tear through the sky at an impressive speed and leave a blazing trail behind all the way down to the forest canopy.  She could see the hole in the treetops, circumvented by fire, that she had left in her wake.  She couldn't help but let out a very amused laugh, stopping her flight to soar forward at very high speeds and listening to the wind as it buffeted her body.  She could feel the energy within her beginning to decrease, but she wouldn't stop even if she needed to; flight was a primal enjoyment for the unicorn, and flying while projecting fire onto your own body and remaining largely unharmed by it simply left her giddy with the incredible display of her growing power.  

After circling the heart of the forest several times, Twilight began to feel a slight fatigue.  The last of the excess was leaving her body, so she extinguished the flames and flew back down toward the hole in the canopy that she had left, reentering it and finding her cloak one more time lying in the grass awaiting her.  The trees had already healed up from the wounding blaze and were on their way to regrowing the dome, but Twilight had more than enough room to get back through.  She landed by the pond, glancing around at the beams of light pushing their way through the smoke left by her near-self-immolation.  She couldn't help but smirk at the raw might of her magic, and she vowed to return to this place for another sample of that fluid: if she could find the proper dosing (she thought) she could easily give herself an extra 'boost' should she ever need it.

She trotted back over to her cloak and book, kneeling down next to them and catching her breath a bit.  She was extremely fatigued from that level of intensity, and realized that her nose was bleeding again, though she just pressed her already damaged cloak up to her muzzle to retain the bleeding and opened the book.  "Well Iago... I'm still here, what else ya got?"

"Okay, you win.  I'm very, very impressed by that, Twilight Sparkle.  Most creatures would have died attempting such a thing, or would have just panicked until they burst into flame, but you... Oh, you.  Not only are you more than worthy of being my student, but it would be my honor to continue to teach you."

"I'm glad you think so, and I'm also glad that you saw everything... I was worried nopony was watching...  I wouldn't believe it myself if I hadn't looked."

"I don't 'see' things in the same way that you do, Twilight Sparkle.  In the absence of eyes, I cannot take in the light of this world.  You could say I've been blinded by death, but in the same way that a bat locates its surroundings by listening to the echoes of its voice, I can see everything around me by listening to the echoes of the magic of the world.  What you did just now lit up my world like a hundred suns... It was glorious."

"Well then, I suppose it's time to go home.  Lucky me for having a little shortcut." Twilight punctuated her sentence with a giggle, feeling as though she'd surpassed her teacher's every expectation: something that would always make her feel like a little filly again.  She picked up her cloak and hid herself as best she could, levitating her book behind her and taking to the skies once more.  The unicorn brushed her way through the already closing hole in the canopy and skimmed the treetops toward Ponyville, enjoying once more the feeling of air rushing past her body.  Despite some of the events that had transpired, Twilight had a great day, and it would only get better.