Canterlot Castle, surprisingly, actually did have a war room. It didn't get much use, because Equestria was a realm of peace, friendship and harmony, and there were few entities crazy, stupid or suicidal enough to wage war on a nation whose benign maternal authority figure could express her disapproval with a strategically placed solar flare. But the growing crisis in Ponyville had led to the old room being aired out, dusted, and prepared for the gathering sitting there now.

In the high throne sat Celestia. A third of the way around the table sat Luna. Another third of the way around sat the newest member of royalty, Twilight Sparkle. In between them sat the Bearers of the Elements, Zecora, a badly scorched Shining Armor, and a disgruntled Discord. They were all debriefing, and trying to analyze their new enemy in the aftermath of their third encounter with him.

"What I want to know is why Discord bailed on us!" Rainbow Dash scowled. She was exceptionally surly; magic had been unable to make her or Fluttershy's feathers grow back instantly, and she was reduced to walking around with knitted wing-cozies to hide her embarrassing naked wings.

"I have to agree," Twilight Sparkle said. "That seems kind of important. Why did you run, Discord? You're one of the most powerful magic creatures in Equestria if not the world. You should certainly be more than a match for some wizard with an amulet."

"That was not merely 'some wizard with an amulet,' as you put it, Twilight Sparkle," Discord said, making quote marks in the air. "That was the Alicorn Amulet."

"So the Alicorn Amulet... overpowered you?" Fluttershy said.

"It's not so much a question of relative power, dear Fluttershy," Discord said blithely, "as a question of balance. Whoever or whatever this Darth Vulcan is, the power that he uses is almost a perfect opposite of mine."

Twilight looked serious. "I thought I was imagining that," she said. "I saw how you and he seemed to, well, cancel each other out..."

Discord nodded. "Two points to the studious alicorn," he said. "his magic and mine basically neutralize one another because of their opposing natures."

"Wait, you're saying he's the opposite of you? Do you mean this jasper is some sort of dark wizard of order?" Applejack was disbelieving.

Discord shook his head. "There's more than one kind of opposite," he said impatiently. "Look--" he pondered for a moment. "Ah, I have it." He snapped his fingers and a perfect ripe red apple appeared over the table. "Okay, everyone, get out your pencils and paper, it's pop quiz time. What is the opposite of a ripe red apple? Go on, go on, write your answer down..." After a moment's hesitation every pony present wrote an answer on the little cue cards that had appeared in front of them. "Okay, pencils down. Applejack, what's your answer?"

Applejack shrugged. "An unripe green apple."

Celestia hmmed. "I put down 'an orange,' " she said.

"I did put down "an apple core," " Luna confessed.

"I said 'a rotten apple.' "

"Me too. Except I said green and rotten."

"You see?" Discord said. "There's more than one way to be an opposite of something."

Twilight's face lit up with understanding. "Oh, so you're saying that this Darth Vulcan's magic is a mathematical opposite of your own along a different mathematical axis," she said.

Discord regarded her with a droll look. "No, I don't think I would ever say that," he said. "But that is essentially correct."

"But you still shoulda been able to whup him," Dash protested. "You got way more power than he does, right?"

"That remains to be seen, Rainbow Dash," Celestia pointed out.

Discord shook his head. "And again, it's not just about relative power. He uses magic. I am magic. It is more... innate to my makeup. Even though I'm heaps more powerful, he can tolerate losing his juice better than I can. Me trying to neutralize him would be like trying to put out a flood with a fire. He would survive and eventually recuperate. I wouldn't." He drew a forefinger across his throat with a "krrrkkk" sound. His head popped off his neck and flopped to the table. "In fact we were very very lucky. Not every opposite interaction results in things just fizzling out," the head went on. Discord lifted his head back up and set it on his neck again. "In fact, sometimes there's a rather large bang."

Twilight shuddered. "Matter and antimatter," she said. "Complete protonic reversal..."

"How big a bang are we talking?" Dash asked apprehensively.

"Let me put it this way," Discord said. "How fond are you of this side of the planet?"

"Oh... my..." Fluttershy said.

"Oh don't worry too much," Discord said. "It's only a concern for me because I myself am, how shall we say, dimensionally exotic." He briefly turned into a moebius strip and a tessaract, then changed back. "He's not going to bump into anything else in this corner of the multiverse that will make him go boom. But you can forget me interfering with him in any way, even indirectly. I might survive a run in with him, I would only lose a portion of myself... but I have no desire to find out if I can survive having half my backside blown off, either."

"Thank you for your input, Discord," Celestia said with all sincerity. "Is there anything else you would like to add?"

"One thing," he said. "It should be self evident to you all that he's not from this world, or even this reality. Don't expect him to play by your rules. Or even mine. I get a vibe off him that gives even me the shivers. He's a lot less powerful than me, but he more than makes up for it by not holding back." He stood up. "I'll be in my pocket dimension until this is over, one way or another. If you need me-- well forget it. Ciao." With that, he looped around in on himself, disappearing with a pop.

"Well, that was unnerving," Shining Armor muttered. "And what did he mean that it was obvious he wasn't from this world?"

"Oh, sho nuff," Zecora said. She had completely given up on her accent and seemed to be relishing using her own native patois. "He's got da Alicorn Amulet, don't he?"

The others looked to Twilight for an explanation. She looked... embarrassed. "We... I... tried to destroy the amulet after we got it away from Trixie," she confessed. "But it proved to be indestructible. So I decided to dispose of it by dumping into a portal into the interdimensional Void."

Celestia looked astonished. "You cast a vortex portal? On your own?"

"Only a little one!" Twilight protested. "Just for a few seconds. Long enough to chuck the amulet in..."

"Still. I don't know whether to be upset or impressed," Celestia murmured.

"Considering the inevitable results, I'd settle for 'appalled,' "  Shining Armor said.

"Fie, Twilight Sparkle!" Luna exclaimed. "Wast thou not taught more responsible behavior than to be chucking things, willy-nilly, into the Void?"

"It was only a LITTLE portal!" Twilight protested again. "And it didn't even have a targeted outlet. The amulet was dangerous! It had to be disposed of!"

Celestia held up her hoof. "In all fairness, while opening a vortex solo was rather risky--" she gave Twilight a Look. Twilight winced. "It was obviously a calculated risk. The odds of anything dumped at random into the Void coming out of the infinite at all, much less coming out on a world with intelligent life capable of using its power, is infinitesimal."

"And yet here we are," Luna noted dryly. "Methinks of the time we caught that one unicorn student of thine dumping his household garbage into the Void." She paused. "Zounds, that Shoggoth was furious..."

"Um, not to be too obtuse, but am I the only one concerned about how the amulet seems... different?" Rarity ventured.

"How do you mean?" Celestia asked.

"Well, the last time any of us saw it being used... the user, as I remember, wasn't just corrupted, she was... irrational," Rarity said, waving a hoof. "Doing daft things like outlawing wheels because she didn't trust them. That sort of thing. This Darth Vulcan character seems, well he's certainly evil and villainous, but he also seems to still have all his marbles."

"And cunnin'," Applejack said somberly. "He took apart Filthy Rich's whole life like a jigsaw puzzle. Never even touched him." She looked sickened. "And what he did to Diamond Tiara..."

"How fares the child?" Luna asked gently.

"Unharmed physically, thank the Maker," Twilight said. "A few scratches and bruises, but those were apparently from escape attempts. Darth Vulcan kept her clean and fed. But inside... she's just broken." Twilight hung her head. "Barely speaks, won't leave her room, barely gets out of bed...Filthy Rich has nurses looking after her 24-7..." It was left unsaid that the nurses couldn't heal whatever wound Darth Vulcan had left on her.

"Could I speak with her?" Shining Armor said. "I want to question her. She might have seen something, or give us some insight into Darth Vulcan's operation, or how he thinks..."

Twilight shook her head. "I can ask, but I don't know if Filthy Rich will cooperate," she said. "He's furiously protective of her right now. I spoke with her, you can review my notes, Shiney, but I don't know how much you'll learn. This much she did tell us:  He has a rapidly growing library. I already catalogued all the books he stole. All magic textbooks, from every imaginable grade level, and he's gotten more since then. He's learned to read now. And he's been practicing new magic every single day."

'He is learning our world's magic," Luna said ominously. "And at a prodigious rate, apparently."

"But he was already powerful and dangerous when we first met him," Fluttershy said in alarm. "How much more powerful is he going to get?" Nopony at the table cared to speculate.

"Another thing," Twilight said. "Diamond Tiara said he can't seem to take the medallion off."

"Can't, or won't?" Applejack hedged.

"Can't. She saw him fuss with it once or twice... trying to pull the chain over his head, or unclasp it-- he always gave up. He has to slide the armor around his neck on and off under it."

"I thought that only the pony wearing it could take it off!" Pinkie said, puzzled.  

"And the magical aura is different... when Trixie wore it, it turned her eyes and her magic field were red. His eyes seem to glow red sometimes, but-- usually it's this mix of purple-green-black..."

"It may be," Celestia said ominously, "that the Amulet's trip through the aether of the Void changed its properties. In fact I'd say it's obvious that it has changed somehow. Anything we may have learned about it in the past may no longer apply." She brooded. "We need to focus on the one who's bearing it. What specifically do we know about this creature?"

"He's really mean," Pinkie Pie said. "I mean, like, angry mean. All the time." She thought for a moment. "And he really hates Ponyville. And ponies."

"That's a bit presumptuous and general, isn't it?" Rarity said.

"Well he was all 'Ponies are stupid' and 'Ponyville stinks' and Rarrr and stuff--" Pinkie Pie struck a pose, snarling like a monster.

"He's also cunning as heck," Shining Armor admitted. "From the moment the guard tried to ambush him to the moment he did his second attack on Ponyville, he was playing us all like a harp." He ran a hoof over his close-cropped mane; magic had removed the scorched hair and set most of his burns to healing, but his tail and mane were still a long way from where they'd been, length wise. Plus they felt sort of crispy... "And he's ruthless in a fight. He bathed both of us in a fireball, just for a momentary advantage."

"And he's got Diamond Dogs working for him," Rarity said. She gave a small shudder. "Though I don't imagine it would take much to get those uncouth beasts to come to heel..."

"Don't forget, he has control of the plants and animals of the Everfree," Fluttershy said softly. "He sent the bats after the guards, and he wrapped us up in those vines... and the timberwolves...."

"He changed the magic binding them together so they were under his control. I didn't even know you could do that!" Twilight said.

"Another thing to note about him," Luna said, unusually quiet... for her, anyway. "He is vengeful. Very vengeful." She gave the room a cool, passive stare. The only sign of her emotions was the faint shiver in her wings. "Moreso even than I was as Nightmare Moon. For a single slight, a single perceived betrayal, he conspired to utterly destroy a pony. For a single day's ill grace to him, he has plundered an entire village. One can imagine what dire wrath he holds for those who have thwarted him directly."

"He threatened to d-d-destroy Discord," Fluttershy whimpered, hiding behind her mane.

"And as casually as somepony saying they would pick up a gallon of milk at the store," Rarity said. A chill settled around the room.

"Y'all can see why ah moved outta dem woods heah," Zecora said. "Ah figured ah better move into Ponyville foah he decided t'give me the same 'generous offer' he gave Filthy Rich, an' decided he din't lahk mah answer."

"It is unfortunate that our first encounter with him was so confrontational," Celestia said.

"Hey, I didn't start the riot, he did," Rainbow Dash sputtered. "I show up, everypony's running and screaming and this- this minotaur-robot-demon thing is standing in the middle of town bellowing about the Princesses. What was I supposed to think?"

"Nopony is accusing you, Rainbow Dash," Celestia reassured the touchy pegasus. "You can hardly be blamed for taking preemptive action. Ponyville hasn't exactly had much good luck with unexpected visitors this past year or so. And we've all had a few stereotypical run-ins of late."

"Exactly. Nightmare Moon: Dark, covered in armor, and evil. Sombra: Dark, covered in armor, and evil. This guy: Dark, covered in armor, and what a surprise-- evil! Pardon me for noticing a pattern," Dash snorted.

".... But all the same, it is regrettable," Celestia went on. "I doubt that things would not have ended up the same, but it is still a missed opportunity.

"Of more import at the moment is his laying claim to the Everfree and all in it," Celestia's expression turned serious. "Which includes the Castle of the Royal Pony Sisters."

"But that old thing is nothing but a ruin," Applejack said. "Why's it so important?"

"Not everything was removed from the castle," Celestia said. "In fact it was abandoned in great haste, so many things of immense value are still there, magically preserved. Many artifacts, major and minor. The contents of at least one of the libraries, which contains many tomes of ancient magic and other knowledge."

"And this guy loves his books," Pinkie Pie said. The others nodded.

"More important is what lies BELOW the Castle," Luna stated. "The Tree of Harmony, from whence the Elements of Harmony came."

Every eye was riveted on her. "You mean these things are, like, fruit off a tree?" Rainbow Dash exclaimed, tapping her necklace.

Celestia raised a hoof and opened her mouth to correct her... then lowered her hoof, a perplexed expression on her face. "Well, technically--" She shook her head. "Whatever. The Tree is tied into the very foundations of our world-- its structure, its magic. My sister and I knew but an inkling of its power and purpose. We dared not tamper with the tree ourselves, gleaning what knowledge of it we did at a remove. Suffice it to say it is incredibly old, incredibly powerful, and incredibly important.

"Discord himself could not lay a claw upon the tree," Celestia said. "But Darth Vulcan, with his strange magics, might be able to breach the protections upon it. As preferable as it would be, we cannot stand aside and let him claim the Everfree as his own. If he should learn of the Tree... and gain control of it...

"Then Heaven help us all."