Final Crisis of Equestria

One of the royal staff reported to Princess Cadence, the highest ranking figure in Equestria. "The royal guard will protect us for a while, but this is impossible. We're being invaded by a living mood-swing on a planetary scale. No magic in the Kingdom is working"

"Tell the Wonderbolts they're overdue to take some action, and ... We need my sister-in-law and her friends."

Zecora had considerable survival skills, which allowed her to avoid the Diamond Dogs who were chasing her. She knew with the right concoction she might be able to ease the emotional state of all the ponies. But only if she avoided her pursuers. When one of the dogs was about to sick his paws into her, Zecora ducked and a grey blur knocked the Diamond Dog unconscious. Derring-Do helped Zecora to her feet. The Zebra smiled "I thought you were a fictional, but it seems you are a pal."
Derring Do positioned her back-to-back with Zecora so they could help defend each other from the rest of the dog pack. "I thought you were an evil enchantress, so today is full of surprises."

Twilight thought she was just sheltering her neighbours from the invasion, but ended up receiving a monolog...
"You fought me as Discord, that was just recreational chaos that proved to me you're the one Equestria needs right now. I used to be known as Star Swirl The Bearded, and I can help you, save everything. But (and I'd never thought I'd say this) we're running out of time, so just call me The Doctor."

And that was the start of Twilight's role.

The Wonderbolts and the Shadowbolts battled each other in the sky, matching each other almost perfectly. They cut through the air and tried to trap each other in their jetstream's. But with Rainbow Dash having joined the Shadowbolts, it was obvious which side would win the dog fight - until a Sonic Rainboom knocked the Shadowbolts out of the sky. While the Wonderbolts recovered, Rainbow Dash explained her motives, "Soarin, listen to me, I just joined the Shadowbolts to avoid capture and find out information, this is where we can turn the tide"

"Unearth the smooze" cried Applejack, having been recruited into the hivemind.

Most of the high society of Canterlot had no issues conforming to the doctrine of hatred and ignorance. Rarity was among those who became sycophants to the new world view. But no matter what kind of viral evil infected the world, in her heart she would also retain some self-respect, and it was that part of her that stung when she saw Green Apple Acres converted into a mining site.

"I can understand a bad trend in the fashion industry, but seeing the landscape ruins is quite literally the worst possible thing, I guess....it is on!" and from a sidebag nobody noticed she was wearing she pulled out a fashion accessory "Applejack, you need this!" And when her trademark hat landed on her head, Applejack remembered who she was.

Mare-Do-Well stood atop a building, the mask pulled over sharp facial features and her cape hanging between her large wings. she gave her intelligence to Rainbow Dash.
"It's Trixie who started all this. She's the key. Displace her quickly enough and you might be able to end this. She's radiating fear and loathing through the air. you'll have to move quickly before you're affected yourself."

Rainbow Dash listened. "I can do that... but who are you?"

All Mare-Do-Well had to answer with was "I... ...Thank you... ...and I'm sorry.."

Nobody could perceive what was going on. Everybody thought Pinkie Pie was arguing with a pile of props. But anyone in touch with Pinkie's senses would hear the props talking back. Rocky told the neon pony, "Pinkamenia, We'll always be with you, but your friends need you too. Without you. You need to help awaken the king."

That was when the tide turned.

In a regular room on the regular world, humans slept, but one person had to wake up to meet their dreams face to face. soon as she saw the girl in her room, it reminded her of her greatest adventure. "My name is Megan, I've been trying to get somebody to believe me about when I met ponies. Ever since I was seven years old."

"My name is Twilight Sparkle, I'm ready to believe you."