On the contrary, all Tartarus did not break loose. Technically, it already had. There were already many ponies running around screaming their heads off[1]. The Crusaders only screamed for one or two moments before adopting clear heads again. Twilight and her friends quickly grew composed.
[1]: Would Ponyville ever learn how not to panic? Probably not. Although, to be fair, they were only scared because of the spells specifically meant to make them scared, but that was besides the point.
"Well, that's not good," Applejack stated, helpfully.
"Like Tartarus it is!" exclaimed Dash. "Do you know what that thing could have done to my reputation if anypony saw me when that happened?" She shuddered, not daring to think of the ponies laughing at her and destroying her well-built reputation of bravery and fearlessness... Blast it, she'd already done it.
"Darlings, have you noticed we haven't been scared yet?" Rarity asked, suddenly, looking back at the knife. "Ponies farther away from us are turning tail, but we're just fine."
"Ah, that would be me," Amoris explained, smiling. "I wasn't able to dismantle the spell, but I placed exceptions for all of you and Spike." Only now remembering to get him, she teleported him over, where he started to launch into a panicked explanation about what was happening. "Yes, yes, we already know," Amoris said, stopping Spike before they would have to sit through that. "You're safe because of me." Spike was thoroughly satisfied.
"Can I sing to stop it?" asked Sweetie Belle, looking at the knife sceptically.
"If my speculations are correct, you sang to start it. And if I couldn't sing to stop it, neither can you, especially with that lack of control." Amoris sighed. "If I can't stop it, there's the chance that only you can, and so we need to build up control in you and quickly."
"I can try and contain it," Twilight said, and before Amoris could think of objecting, Twilight's horn lit up and she surrounded the knife in a barrier. It stopped moving, but it didn't stop scaring anypony that looked at it. So, Twilight made the barrier opaque.
"No, don't!" Sweetie Belle exclaimed. As soon as Twilight made the barrier opaque, the knife drained the magic from the shield to strengthen itself and then began moving again. Sweetie sighed. "It can use the magic of others to make itself stronger... Especially if it can't fulfil it's purpose."
"Um... Oops?" Twilight asked, blushing sheepishly.
"I don't think the magic in a shield would be very much for it, though," Amoris rectified. "Now, it's time to-"
Discord appeared with a flash and an explosion of snow, coating the others in white. They all quickly shook themselves so they could see who had done that. "Yoohoo! Sorry I'm late, friends, I had a bit of difficulty with the candles." He blew on a bit of flame that had just sprouted on his paw, putting it out. "Hmm, looks like it's not fully gone. Note to self: Don't mould so much with the chandeliers next time."
He blew out another flame on his claw this time (which perturbed Twilight) and then donned glasses and a plaid suit. "I'm suited and ready to teach, my dear," he said, bowing to Amoris and Luna. He booped Luna's nose with his paw and she scowled. "Oh, don't be so glum. You should be honoured that I'm here to help! I'm very good at singing, you know." He opened his mouth and put a claw to his chest, but Luna interrupted quickly.
"Yes, we know, thou canst sing well, let us get on with it." The Crusaders giggled and Discord pouted.
"You can't control Heart Magic any more than the Elements of Harmony can control Chaos Magic," Amoris explained, frowning. "You won't be any help at all."
"Oh, sure I will," Discord said, straightening a bow tie that hadn't been there before. "Luna can't use Heart Magic and she taught Sweetie Belle perfectly well. I mean, it isn't like her carelessness caused Sweetie Belle to restart the Knife. But if it were, I of course would reprimand her, because that's what friends do. Because I'm her friend. Right, Luna?"
"I am most certainly not friends with thee," Luna retorted. "However appreciative of thy gift I am. And that is not amusing." Luna scowled again.
"Oh, fine. But still! I simply must help with this. As a good friend, it's the least I can do." Discord held up his claw and began to snap his fingers as he listed what he needed, creating each thing in turn. "Now, we need a blackboard, some chalk, a dolphin, a bat, preferably vampire, not Fluttershy, and-"
"The best thou canst do is leave," Luna said, huffing. "We do not need thee." Discord literally deflated, the object he'd summoned disappearing, before he curled around Luna as a blanket to add to her coat.
"Why, don't make such quick judgements as to whom you do and do not need," Discord reprimanded. "Goodness me. Just because I am not an orderly being does not mean I can't be a perfectly good teacher. Helper, at least."
"You couldn't possibly help in such a terrifyingly dull outfit!" Rarity exclaimed, suddenly. Discord as a blanket still had the plaid suit on. "Plaid is fine if you know how to pull it off, but these colours!" They were a drab green and brown, with a hint of drab red. "I don't need a Knife to scare me with that monstrosity around."
"And here I thought you would like my choice in fashion. I thought I'd learned so much from you. It seems I'll have to try harder," Discord said, with obviously fake dejection. But that coat you made for Luna! It looks absolutely frabulous on her." Discord curled off of Luna and returned to his original shape, booping Luna's nose again. "Stunning." Luna frowned in confusion at the compliment, her eyebrow raising. Discord took no notice.
"Well, I'm glad you like it! I worked hard on it. Oh, and I have so many more in store to make!" Rarity exclaimed, excitedly. Then she drooped. "It'll have to all wait until after this big mess." Discord conjured up sea green suit around himself, the same colour as the fluff from Luna's coat. It had an abstract gold paisley pattern.
He teleported next to Luna and smushed their faces together, side by side. "Don't we look great?" he asked, as Luna tensed up and pushed him away, an annoyed scowl on her face.
"Now that looks much better," Rarity said, her eyes gleaming. "Keep wearing it! The abstract positions of the pattern actually complements your asymmetry. A hard task, I should say."
Discord gasped. "You don't like my asymmetry? Well, how rude. I was born like this, you know! Well, not born, but that's a story for another time." Discord closed a book he was holding and threw it into nothingness, before remembering he was holding another and throwing that one out too.
"I never said I didn't like it, just that it was incredibly hard to make fashionable!" Rarity exclaimed. "In case you're wondering, that was not a compliment." Both she and Discord harrumphed.
"Ah, fer one, don't think Discord would be any kind of help right now," Applejack said, scowling.
"And why, pray tell, would that be?" Discord asked, interestedly. "Do you think I am incompetent in matters like this because I'm the god of chaos? Last I checked, that was not a deterrent of any sort. Or maybe you just don't trust me." He laughed. "Wait, we're friends, and friends trust each other."
Applejack opened her mouth, and then closed it. "Look, if you somehow think I have bad intentions, why not be that lie detector you are thanks to the Elements?" Applejack frowned, but her ear flicked and she listened closely. "I have no malicious or harmful intentions. I sincerely want to help. There. Do you trust me now?"
Applejack's eyes widened as she realised he was telling the truth, but then she grew sceptical again. "How do ah know ye'r not jus' twistin' the results?"
Discord was taken aback. "I would never do that!" he exclaimed, sincerely. "But to ease your suspicions: The Elements of Harmony negate chaos. Unfortunately, the Tree won in that little power battle of ours. Always one-upping me, that one. So! You will know if I'm telling a lie." Applejack sighed and tipped her hat in defeat.
"I think it'd be cool to see Discord helping with teaching," Rainbow Dash added, surprising the others. "What? You know how crazy he is. He might keep this from being a borefest."
"I agree!" exclaimed Pinkie Pie. "Discord is super silly but he can be super serious at the same time!"
"But-" Luna tried to protest, but Fluttershy finally spoke up.
"I think we should let Discord have a chance, Princess Luna," she said, shyly, but not too quietly. "He really wants to help."
Luna frowned once more. "... Fine. I shall let him help. But know that it is on your heads if this faileth because of him."
"It won't," Fluttershy assured her, her voice steady. She was sure of her friend.
"If thou sayest so." Luna sighed.
"So it shall be!" Discord exclaimed, and then launched into talking with himself. "We need to figure out just how Sweetie Belle can control her emotions." The ponies expected him to create a duplicate of himself, but Discord wasn't having that. A mouth on his claw spoke instead. "Oh, but have you seen that storm?" "You know, she doesn't even know what those emotions are," added a third mouth on his stomach, reminiscent of his little musical number with Cadence and Twilight.
"That is the main problem," Amoris said. "How can she control her emotions without knowing about them?"
"Clearly, she needs to subconsciously control them somehow," Twilight added. "Or we could elicit them to actually show."
"That could have adverse effects," Luna replied, frowning slightly as she thought. "There are many emotions that swirl in her heart. If the bad emotions come to the surface and stay, it could ruin her innocence in terms of emotions."
Sweetie Belle came out of her thoughts and looked up at the divine discussion. "Well, how about you tell us how you got to control your emotions, Amoris?"
Amoris thought about it. "I had a different situation than you, you know. I knew what my inner emotions were. You don't. I'm not sure I'd be very helpful." But, as they were beginning to find out, Amoris was very arrogant concerning herself, and so naturally, she had to talk about herself. She could spare some time anyway, since she could shorten it.
"As I started my reign," she began, "a lot of emotions began to surface. Sometimes the many creatures could be so insufferable, and I had anger and malice and soon hate boiling in my heart. So I took up singing, trying to get a break from the annoyances. I hummed in court, I vocalised when I was alone, I learned to play instruments and even created a few.
"I began to let my roiling emotions emotions into my music, and slowly, the music really did calm me down. The emotions began to subside as I let my singing peter them out bit by bit. Now I hardly even know if the emotions are coming. I sing from my heart and let them resolve themselves." She smiled lightly, and then frowned.
"But you, Sweetie Belle? Singing from your heart isn't helping. Yes, it's giving them an outlet, but I think it's just making them stronger." She scuffed the snow with a hoof ever so slightly, maybe a bit irritatedly.
Sweetie Belle paused, mulling this over. "Huh. That's a bummer."
"Clearly, we need something that doesn't have anything to do with the Heart Song to get this right," Discord said, with his usual mouth. His claw quickly spoke up. "Why not compose sheet music for her to follow?"
Realisation dawned in Luna's eyes. "If we create a song for her to follow, one that controlleth her emotions for her, that may succeed for long enough that Sweetie can stop the Knife!"
Hmm. Maybe that would help. "I'll get to that right now," Amoris said, summoning up a paper and beginning to project notes onto it with a spell.
Meanwhile, the Knife had begun moving around much faster, terrorising the ponies in the town with horrible fear of nothing at all. Twilight's friends tried their best to reassure the ponies that came their way, but it was to no avail. The Knife was too strong for petty logic to break its hold.
Nearly all of the ponies without an exception had been scared by now. There was hardly any damage, though, other than that which the ponies occasionally knocked over in their panic. But collateral was kept to a minimum. The Knife's job was not to cause destruction, just fear. But even then, so much fear was not a good thing to have. At least it was only staying in Ponyville.
"Mare, this is crazy," Rainbow Dash said, as she redirected a pony that would have barreled into the conversation between the divines. Besides trying to calm the ponies down, they were also making sure that the conversation was not interrupted--this needed to go as quickly as possible.
"Ye'r tellin' me," Applejack droned, throwing an apple into the mouth of a loudly ranting foal.[2] "And it seems to be gettin' worse and worser."
[2]: The ranter was none other than Pipsqueak, the town conspiracy theorist. And of course, the apple didn't hurt him, as stated before.
"Applejack!" Rarity exclaimed, scandalised. "You know better than to use 'worser'!" She huffed and turned away, summoning a gem[3] and throwing it to the side to distract another pony.
[3]: As Rarity's magic skills had been developing, so her gem finding spell grew to the point that she could actually summon the gem(s) found if she needed them.
"Literary effect, or summat," Applejack replied, waving her hoof. "Twilight mentions it sometimes." Rainbow Dash picked up a particularly persistent pony and shot off, depositing him at the edge of the town and coming back in less than ten seconds. She was gradually decreasing her "flat" time as her talent with flying grew.
"Worse and worser," Dash mused, putting a hoof to her chin. "I've got to say that some day." Rarity frowned. "For literary effect, obviously." Rainbow Dash smirked, and Rarity's frown deepened sceptically, but she reluctantly brushed it off.
While they were talking, Fluttershy was trying in vain to calm another scared pony down. Unfortunately, ponies were not animals, and though her magical care for animals was gradually extending to ponies, these particular ponies were under the influence of a magical spell, so Fluttershy's comforting tones were lost on the irrationally scared victim.
"Fluttershy," Dash finally said, as she put a hoof on Fluttershy's shoulder. "It's not going to work. The Knife is too strong. You have to make them leave." Rainbow Dash sighed. She knew that Fluttershy would not be happy about it, but there was nothing for it.
"But look at him..." Fluttershy replied, sadly. The stallion was cowering and shivering in fear. "I know it's just a spell, but that doesn't make the fear any less real."
Rainbow Dash herself was saddened by the revelation. "I know, Fluttershy. I don't want them like this any less than anypony else. So we need to make sure they don't interrupt Amoris and the others so they can figure out a solution faster. As soon as they fix it, the ponies won't be scared any more." Rainbow wasn't so sure that it would be that easy, but she couldn't tell Fluttershy that.
Fluttershy had no such doubts now, though, having been reassured by her friend. If Rainbow Dash trusted them to find a solution, then they would. "Okay then," she said, her voice firmer and she slowly turned the stallion around, shooing him away. He happily[4] obliged.
[4]: If by happily you mean "in sheer terror," of course.
They continued to converse as the divines (minus Amoris, who was writing music) brainstormed. However, they unfortunately weren't coming up with any useful answers other than the first one. Every now and then Amoris would glance at the knife and mutter to herself, before projecting notes again, quickly approaching the end of the song.
Finally, it was finished. "Here we go!" she exclaimed, brightly, presenting the sheets to Sweetie Belle. "All done. This should do the trick!"
Sweetie Belle stared at the sheets without signs of comprehension. "Um... I don't really know how to read sheet music." She blushed sheepishly. "Oh wait, it's upside down." She turned the sheet music upside down at this. "Now it's worse."
One of Amoris' eyes twitched ever so slightly. "One: Only now it's upside down." Her voice was kind, not reprimanding or annoyed like Sweetie Belle expected after her failure. Amoris giggled lightly and turned it over. "Second, you only need to know the first few notes, enough time to start the song." She sang the first four notes to clarify.
Sweetie Belle looked over the page a bit more. It seemed complicated. There were notes on top of each other and seemingly in the same place. How could she possibly sing so many? But she trusted the Heart Song, and began to vocalise.
As she sang the first four notes, the notes on the page sprang to life. Immediately, she knew what to sing and what notes were where, and she rose to the challenge, her heart following the page. Somehow, her voice layered in the notes that were together, singing both low and high and even chords.
In her heart, the usual connection opened up. However, instead of many emotions flowing out, none came at all. She sang the song well, and the magic of the tune itself was working, but there were no emotions in it. Long story short: Nothing happened.
Amoris sighed, disheartened. The very second Heart Song user, snagged by an impossible lack of control. What was she going to do? "Well, that didn't work. Did we come up with any other ideas?"
"Wow, Sweetie Belle, that was awesome!" Scootaloo exclaimed. "It sounded kind of like there were lots of singers but at the same time only you."
"Darn tootin'!" Apple Bloom echoed. "That's yer best performance ah've heard yet!"
"I wasn't really feeling it," Sweetie Belle replied, grimly. "Not as much as usual."
"Ye'r serious?" Apple Bloom asked, surprised. "Dang." She didn't know what to say. That was incredible, and she wasn't even feeling it? She just shook her head in wonder.
"Again, have we come up with any other ideas?" Amoris asked, impatiently. Time was ticking, and they needed to be more concerned about this. Amoris tapped a hoof on the ground in irritation.
"Unfortunately, your highness, we have not," Discord said, in a business suit with a suitcase. He pointed to a presentation with various ideas crossed off, most of them nonsensical and only a few the ideas that they'd actually come up with.
"Hmm... My findings from this are that trying to artificially control Sweetie's emotions simply completely holds all of them back. No matter how intricate it is, it cannot replicate natural control of emotions unless Sweetie Belle knows what her emotions are, which we've established she can't." Twilight quickly wrote down the findings as Amoris spoke them, drawing up a few of her own notes which weren't very helpful.
Amoris gazed at the Knife, and then at Sweetie Belle, before being snapped out of her reverie by Luna speaking. "So, then, what shall we do? We have not any ideas."
Amoris looked at Sweetie Belle, and then at her own hooves, her faced wrinkled in conflict. "I need to go. I'm sure you can all figure something out." And then with a flash, she disappeared.
Everypony in the group quieted, the divines, the Crusaders, and the Elements. "Ha!" Luna finally exclaimed, breaking the silence. "I told you all that Discord would somehow make this fail!" Now everypony was glaring at her. She shrunk back a bit. "Um... We are sorry?" Fluttershy glared harder. Luna frowned. "Fine. Discord, we apologise for accusing you of causing our mother to leave."
"Apology accepted!" Discord exclaimed, with comically large tears in his eyes. He tightly hugged Luna, before letting go and snapping his fingers, creating a life-sized plushie of himself hugging Luna. "Hah! It's perfect."
Luna scowled, and then her expression softened. She lightly pushed the plushie away from her face so she could see again. Before conversation between the two could further and anger be accidentally rekindled, Sweetie Belle spoke up. "So... What do we do now? Amoris is gone, and you didn't come up with anything else."
"I don't really know," Twilight replied, grimly, her face emotionless. "There doesn't seem to be any way to negate what's happening to these ponies. I hate to see them so scared. Maybe Amoris will come back. Until then, we sit down, and we think. There's nothing else for it." She sighed, and there was a depressing silence.
"There's got ta be a way!" Applejack suddenly cried, breaking the silence. "Ah refuse ta believe that we can't do nuttin' without that pretty pink princess!"
"Queen, Applejack," Discord replied, tutting. "Know your titles." He began to unroll a very long scroll, but Rainbow Dash stopped it with her hoof.
"That literary effect thing again, or something," she replied. "Probably because 'Pretty Pink Queen' doesn't sound anywhere near as good." She chuckled.
The scroll disappeared with a flash. "You're right! Carry on, Applejack."
"Maybe we kin corral these ponies somewhere where they can't see the Knife," Applejack said, her eyes brightening.
"Last time we didn't need to see the Knife for us to keep going to the Elements," Twilight responded, still emotionlessly. "That won't work."
Applejack opened her mouth, and then suddenly, the Knife disappeared and the panic stopped, the fear subsiding and returning the ponies to a (mostly) normal state. The ponies all shuffled back to their homes, and the immune ponies quieted again. "Huh," Twilight eventually said. "Never mind."
Suddenly, with a flash, Amoris appeared with the Knife in her telekinesis and a cheery expression on her face. "Oh, hello, my friends! Guess what I did!" she exclaimed, in a singsong voice.
"I'd like to guess that it was stopping the Knife..." Fluttershy whispered.
"Unfortunately for you, no." Amoris chuckled lightly. "You need to get better at guessing." Before anypony could guess further, Amoris continued. "Well, since you obviously won't ever get it, I joined the Knife!" The singsong tone was beginning to become infuriating.
In unison, the others replied, "You what?!"
"She ain't lying," Applejack said, next, forgetting that Amoris was the master actor. That, however, did not mean Applejack wasn't right.
"Nope! I'm not. Would you like to know the reasons? They're very interesting!" Amoris giggled when the others said nothing, preferring to scowl at her. "Well, one, I joined it because it was cute! Trying to cause havoc with its little irrational fear spell, however powerful it is."
"You think that monstrosity is cute?" Rarity asked, horrified.
"Actually, I think it looks kind of cute," Fluttershy whispered. "Although I'm not sure that's what she meant."
"Obviously," Amoris droned, but in a cheery way, however impossible that was. "Anyway, I have a second reason, if you'll all bother to listen. Which I'm sure you will. To put it short: I'm jealous!" She had no qualms about admitting that at all. She was very arrogant, after all.
"You see, all those years ago, when I discovered my use of the Heart Song, I realised that I was going to be the absolute best musician ever, not just past or present, but future, as long as nopony got my magic. I 'one-upped every musician ever,' as Discord so eloquently said." Discord bowed and the sound of clapping filled the air as rose petals floated down around him.
"Not the time, Discord," Twilight said, gritting her teeth.
"Anyway, then came Sweetie Belle." Amoris glared at the filly in question. "Going up and somehow gaining the powers I thought nopony would ever have. But she had potential. So much potential for great power. The chance to be better than me. So I help her, and then I find out that she can't control her emotions, and even worse, she doesn't even know what they are! It's pathetic."
Sweetie Belle looked hurt. "You do not talk about my sister like that!" exclaimed Rarity, indignantly. "Just because you hit a small hitch like that doesn't mean you can just brush her off!"
"Your care for such a useless little filly is adorable. But alas, I really don't care. What I do care about is the possibility of anypony ever having my Heart Magic again. So, I've decided upon the perfect solution! Add a hate spell to the Knife and then spread it across all of Equestria. Everypony rips each other to pieces, no more ponies, nopony to get the Magic." Amoris giggled.
Twilight and her friends were taken aback. For all the villains they'd faced, none had ever wanted to kill anypony.[5] "Unfortunately, it won't work on you, since I couldn't take off those exceptions, but you're all girls, and unless you can magic foals out of nowhere, I don't think that's going to get anywhere." She consciously left out Spike, who was considerably hurt by the total dismissal.
[5]: Besides the various consequences of an Eternal Night, of course.
Luna's emotions were conflicting terribly. She couldn't bring herself to hurt her mother, but this was a dire circumstance. Still, she just couldn't. Thankfully, what she did know was that no matter what, ponies did not kill each other. Ever. Spell or no spell, it didn't happen. She hoped her mother didn't know that.
"You're a monster," Rainbow Dash said, darkly. "Killing everypony in Equestria? Also, villain cliché number one, the villain says her plan. I mean, come on." Rainbow Dash crossed her arms.
"I can do that because I've already started it!" Amoris exclaimed, a wide smile on her face.
"No you haven't," Pinkie Pie said, grimly. She had not spoken through this entire time, and her hair was beginning to flatten from the prospect of a land without any laughter at all, a land where nothing she could do would ever make anypony laugh.
Instruments from nowhere began to play a dark, driving, and dissonant tone with anger in its undertones. Suddenly, a bubble of dark red light burst from the Knife and expanded, covering all of Equestria in mere moments. "Well, I just did! So, there goes your little cliché, Rainbow Dash. It'll be fun watching you all try and fail to come up with a way to help Sweetie Belle in time." Amoris giggled. "Cute."
And then Amoris and the Knife disappeared. The ponies huddled together, watching in horror as ponies from all around began to exit their houses into the night[6], starting to horribly insult each other.
"Well, I feel like there's only one thing to say in this situation," Discord said. "With fronds like these, who needs anenomes?"
[6]: The day had for some reason progressed much faster than it usually did.[AN 1]