"One thing." Shifting was angling a hoof slowly. "The words you said. 'In darkness, lies can't hide' or something like that? But darkness is... the perfect place for a lie to hide. How does that work?"
Umbra blushed, grey cheeks coloring. "The words are not actually part of the spell... The words in the book, that described it, was more that I was stripping away the different colors that a lie would 'hide in'. Strip away the false colors, in dark, and you're left with the real deal." She gestured at the bat pony that wasn't always a bat crystal pony. "Get it?"
Shifting clopped with understanding. "Got it! Why do you say words at all?"
"Because it's cool?" weakly defended Umbra. "Wasn't it dramatic?"
Shifting burst into a new set of giggles. "It really was! If you like it, then we do it. What else can you do?"
"Shadow walls, that was the first I learned, from the book." Umbra was pointing at the book as she went over that. "But shadow is really good at... negation? Cancelling. Turning things off. I learned a spell to make other spells turn off, and that felt super handy to have around. Bad magic coming at us? I can help! One thing it doesn't have a ton of are the mind whammies."
"Mind whammies?" Shifting inclined her head sharply. "What's that?"
"Sombra, the jerk, was renown for his ability to wrap people's minds around his hoof like it was nothing. He was a slave driver, not just physical-like, but he could get you running in step, on the inside." She tapped at her own head firmly. "Which is part of what made him so scary, because he was not shy about it, at all."
Shifting turned one ear away. "Well, um... good? You don't want to be a jerk like Sombra."
"You're stealing my word." Umbra touched noses with Shifting. "I'm the one that calls him a jerk."
"If he's a jerk, I get to call him a jerk," hotly defended Shifting. "A jerk's a jerk!"
"Alright, alright." Umbra softly nuzzled her friend and mentor. "But that means I have learned very little upstairs, so far. Which is annoying! Cadance just told me how to fix my other problem, but I don't have a spell for that, so I'm trying to muddle through it on my own with limited success."
"Aw." Shifting sagged sympathetically before bouncing up and away. "But you're getting lots of other tricks. What's your flashiest one?"
"Flashy is... not shadow." She curled a hoof to her chin, considering which could be considered flashiest. "Hm... Oh!" Her horn lit with dark magic, eyes flaring brightly with the same as she grappled great shadowy magic with the skill given in part by the body she was in. The room went dark, but only for a moment, the objects in it returning but their colors distorted. "Behold, negative space!"
Shifting reached out to a chair, only to find it wasn't there. "What?" The desk in the room, however, was. She could pat it down and examine it easily. "What is this?"
"Negative space lets us see what has had the most 'impact' on the area. Like that chair? Guessing it was replaced not long ago, so it hasn't built up weight." Umbra glowed with her power, keeping the spell going. "Unlike the desk. People are visible, we have a lot of weight just by being... us."
"Oooo." Shifting was looking at Umbra, who seemed about half again as large, her glowing magic all the more brilliant. In the plane of shadows, a shadow wizard appeared quite large and imposing indeed. "I don't mean this as an insult, but you look very heavy."
That got new laughter from Umbra. "I see how it is, attacking a mare for her weight." She pointed at Umbra. "You're about the same size."
The same size as she had started. Shifting was still Shifting, just with opposite colors in that shadow zone. "Well, this quite flashy, just like I asked. "But what... is that?" She turned to look at a painting on the wall. It showed Sombra, seated on a throne with a cocky smile, looking quite regal.
"That must have been there forever. It's still leaving an imprint even though it's not there anymore. Like the old chair did."
Shifting did her best to grab the painting, but it wasn't there. A shadowy remnant of the past. "Huh... Shadow magic!"
"Shadow magic," sang Umbra in agreement, the room suddenly returning to normal. "Still learning, but I got enough down that I want to not abandon crystal work. Making crystals is fun."
"I knew there was a reason you called me. Not that I would have complained if it was just to show off." Shifting clapped gladly. "It was fun stuff. Except that first spell. Don't cast that on me again please."
"I still think you're just as pretty either way." Umbra perked an ear forward at Shifting. "But I will respect that. Nobody should be forced to be what they don't want to be."
"Thank you," let out Shifting with a relieved sigh. "So, today, let's work on small things." She flashed a big smile. "I hear you're playing O&O. That means you need dice. Dice, you know, actually takes a lot of work to get right. If you want one that rolls fairly and well, at least. If you want a basic blob that sorta looks right, easy. But we're not gonna settle with that, now are we?"
"No!" Umbra sat up tall. "Show me how to make my own magic math rocks."
Shifting burst into fresh laughter. "Math rocks? That's a funny name for dice."
And so the lesson on crafting dice began. From the basic cube onwards to the mighty icosahedron.
Eyes turned to the smugly grinning Umbra as she set down her dice bag. Tumbling free of the bag came a fresh new set of dice, dark purples with bright green stripes. They were her shadow magic dice! Made with shadow magic, well, her magic. But her magic was shadow magic, so it still counted! "I am prepared."
The Story Master laughed softly. "A new set? They look well made. Where'd you get them? I didn't think a store around here offered customs. That is custom, right?" He pointed up at Umbra's horn. "Looks like you."
"I made them," reported Umbra with such satisfaction. "I am a shadow crystal wizard."
"Ooo!" A crystal stallion was waving a hoof wildly. "Can you make me a set? Please!"
Umbra looked to the dice he had. Perfectly serviceable, but also pretty plain. They were a blue color, which fit his pelt well enough. "Do you want it to match you?" She pointed at him. "Or your character?"
His eyes widened like saucers, but before he could answer, the Story Master clopped the table. "That can come after the game. Now, last we left off, there was a bit of trouble. I seem to remember somepony dangling off the edge of a cliff."
Sunburst swallowed audibly, giving away which character was in trouble. The story and game would continue, and hopefully their companion would be rescued.
Umbra looked in the mirror at the dark mare looking back at her. She fluttered her lashes and fluffed up her mane. She was... Pretty, yes. She was a darkly pretty mare. Imposing, with that curved horn and those sharp teeth, but also pretty. A shadow princess! Well, not princess. Princess had a specific meaning in pony land. She had no wings, so she could not be a princess.
She could be a hero! And she was. "Umbra, the Brave and Glorious," she laughed out to herself. "And that's only half the title," she reminded herself out loud.
"Is everything to your liking?" There was Purple, often present, but not always noticed. "I can brush and groom you, honored ma'am. It would be a pleasure."
Umbra angled an ear at her new... servant? Assistant? "You are probably the wrong person to ask, but I'm feeling very... pretty today. I like the pony in the mirror." She pointed at said mirror. "I feel sexy and I like it. What do you see?"
"I see a national hero." She nodded firmly at that. "Worthy of care and maximum diligence. I also see a talented crystal crafter and shadow magic user." Her crystal ears pinned on her head. "If we are being honest, that last part makes me slightly nervous, madame."
"Why?" Even as she said it, it hit her. "Oh!" Umbra turned swiftly to Purple. "I'm so sorry. Um... You are super free to tell me no, but... I do have questions, about that jerk."
"What jerk, madame?" Purple inclined her head faintly. "Has somepony been bothering you? I will gladly report them to the authorities."
"I am the authorities, um... part of them." Umbra worried her hooves together with a strained chuckle. "I meant Sombra." That got a powerful wince out of Purple Polish. "Sorry! It's just... I want to know about him. I want to know what he did right, and wrong, so I can avoid making the same mistakes."
"That is respectable, madame." Purple closed her eyes, breathing softly a moment before they blinked open. "If you can tolerate my slowness, madame, I will try to be of assistance. Let us begin with why the mention of his name brings such a reaction to most crystal ponies." She walked slowly across the room as she spoke. "He was a tyrant in the truest meaning of the word." She looked over her shoulder as she passed Umbra. "You bow your head to Cadance without hesitation. She is your princess, and that is very reassuring. To... him... there was no other pony above him. He was the start and the end. All else, beneath him."
Purple stopped beside a picture that showed the crystal heart, with Umbra smiling in front of it, flanked with both Cadance and Shining Armor. "I am not expressing it well enough. He was not 'above' other ponies. In his eyes, he was the only pony. All others were simply... chess pieces, either for his hooves to move around a board, or being moved by annoyances mounted against him." She turned to Umbra. "Yes, pieces. Like pieces, he cared not a wit to hear of their thoughts. A sacrificial play with a pawn? Standard practice for any chess player, but his pieces were living ponies. And he showed them just as much care."
"Jerk!" hissed out Umbra with even more feeling than usual. "Just... jerk!" She stomped the ground with obvious anger. "I'm so sorry you had to live with that!"
Purple smiled gently. "It is good to see you react that way. One day, I imagine, you will learn his tricks. You will be able to plunge a pony's mind into... into darkness..." Tears began to peek free of her eyes, but she was looking at Umbra directly, forcing herself to continue. "I can only hope you will show greater care for the lives you hold in your hooves."
Umbra suddenly hurried forward, capturing Purple's cheeks in her hooves. "This!" She rubbed those fuzzy cheeks. "This is a living pony. A living creature! She has a name, a nice one." That got an awkward smile. "She has wishes and dreams and she has friends and likes and dislikes. Those are all wonderful parts of being a living thing, which she is." Her hooves slipped past those cheeks to instead hug Purple, embracing her tightly. "We may not always agree, and that's alright. She's alive, and I love her for being just what she is."
Umbra got out a squeak of her own. She was being hugged in return. Purple's trembling arms were around her, drawing her tight. She had a crystal mare, sobbing against her. Umbra gently petted and held the explosively expressing crystal mare. "Shadow can be kind too, not that the jerk ever showed it. I will be shelter, not a master."