Both Twilight and Rainbow Dash were shocked at how swiftly and violently the library was decimated. All that remained of the structure was a large crater with a column of smoke rising from the middle. Tears came to Twilight's eyes, the monument to Tirek's defeat was destroyed in a much similar way to the Golden Oaks Library. Twilight's sadness quickly turned to anger as she came to realize that whatever was hidden in the smoke had bad intentions, and she was going to make it pay.

"Twilight..." Rainbow grew worried for her friend. Twilight had this look on her face that Dash had never seen before, a look of pure hatred. Twilight's rage grew at alarming rates. But then she heard a voice in her mind that could only have belonged to the thing in the crater.

Yes! Let your anger flow through you, let it consume you, let it...become you.

"Twilight!"

Twilight snapped back to reality and saw Rainbow Dash standing in front of her. They were somehow on the ground now, standing on the edge of the crater. She looked around an didn't see any of her other friends. The thought of the worst happening to them came to her mind, and it filled her with dread.

"The...others..." Twilight spoke in a whisper barely above Fluttershy's level. With the blast and the voice, her mind was running rampant at this point.

Rainbow Dash put a hoof on Twilight's shoulder and gave her a reassuring smile, "Don't worry they're fine. When the earthquake started they, along with the rest of Ponyville, evacuated to a safe shelter. Then I came to find you."

Twilight took a deep breath, finally regaining her composure. "Thank you, go back and get the others, but don't give the all-clear just yet."

Rainbow Dash gave Twilight a quick nod and then hurried to the other side of town. Twilight looked up and saw Luna and Celestia descending along with a squadron of royal guards. The guards created a circle around the perimeter of the crater. Twilight simply exchanged glances with the sisters as as they positioned themselves with one on either side of Twilight. Nobody uttered a word during this process. It was as if everyone was preparing for what ever resided in the bottom of the crater. The rest of Twilight's friends silently took up formation behind her. They too also sensed the heavy tension in the air. Then the smoke cleared. The figure standing there on two legs, for some unknown reason, struck fear into all of them.
The figure resembled that of the human creatures Twilight encountered, except she knew this was not a human standing before them. It wore a pitch black cloak with a hood covering everything of its body and face except two beady red eyes. The strangest thing was its arms. The cloak was sleeveless, revealing arms that were completely made of metal, and had long pointed metal claws rather than hands.
The figure looked up at Celestia,

"Hello Princess."

Celestia had a deep frown, and her eyes held some weird, sad determination.

"Hello Guardian."

The figure threw back its head, without somehow dropping the hood, and gave a dark cackle that filled everyone with the urge to turn tail and flee, but they stood their ground.

Guardian glared back at Celestia," I'm afraid I don't go by that name anymore."

"Then who are you?"

"You and the rest of Equestria will refer to me as Master. But I am formally known as The Overlord."

"What happened to Guardian?" Luna desperately shouted.

The Overlord tapped the side of his head, "Somewhere in here, but I can't tell for sure exactly where all the little pieces of his mind went."

Now it was Twilight's turn, " What are your intentions, Overlord?"

"Why, to have some fun. Equestria is a lovely place full of lovely people, and I thought I said to call me Master."

"Are you implying that we will simply bow down to you." Twilight's voice wavered, but held her ground.

"If you wish to survive then yes."

"Now wait just a minute!"

Rainbow Dash flew over their heads and into the crater, stopping inches in front of the Overlord's hidden face.

"Your saying that if we don't do what you say, then your going to destroy us?"

While they couldn't see it, The Overlord was giving them a wicked evil grin. "Glad we understand each other so well."

Rainbow Dash was growing angrier with every word he spoke, "Ya know, it's not the first time that we've dealt with power hungry tyrants like you! We've defeated Sombra and Tirek, who I think your only half as bad as them!"

Then without missing a beat, The Overlord raised a fist and all the guards dropped to the ground dead. Rainbow Dash immediately regretted saying those words. The Overlord quickly snatched her out of the air and pure terror crossed Rainbow's face. He held her at eye level.

"Listen very, very closely you insolent whelp, I withhold a power far stronger than anything you have here-"

"And that is where you're wrong."

The Overlord was struck by a bolt of Luna's magic, knocking him to the ground and releasing Rainbow Dash. She flew back over to her friend's who huddled around her. Celestia and Luna were now in his face.

"You may have your vile ways," Luna continued, "but there is a magic that resides here that is more powerful than you could possibly hope to overcome."

The Overlord recovered quickly and sent Luna flying back with a burst of force.

"Why you--"

"Stop!"

Celestia moved in front of him, a look of desperation in her eyes, "I know that your in there Guardian, please give me a sign of my mentor, my friend."

The Overlord sent her flying out of the crater as well and followed with a single leap. Celestia laid on her back, unable to move and completely vulnerable. A sword made of shadows appeared in The Overlord's hand giving off wisps of smoke. He raised his sword ready to strike Celestia down, when he was suddenly tackled by Rainbow Dash. But she simply passed through the dark figure. She looked around in confusion, which quickly contorted into a look of agony and fear when the dark blade was plunged into Rainbow's back.

Author's Notes:

I think that I should mention that any feedback, positive or critical, is much appreciated. I'd like to hear from y'all so I can improve my work and get a better idea of which direction to move in.