The ponies had gathered around the Tree of Harmony, waiting for some indication, some sign of what to do, but the tree was silent, its glow dim. 6 ponies and one dragon sat grimly in the dark cave around the physical form of the great spirit. Twilight had left a short time before after they had spent some time with the tree, she said that there was something important nearby that she needed to get. She had assured the others that she would be back quickly.
"What if nothing happens? I know this is the tree of Harmony and all, but I can't imagine it just saving the day out of nowhere," Sunset mused.
"Well it did before, but then again, we had to get all these keys and learn about friendship and figure out this great truth at the last moment," Pinkie rambled.
"Well I don't recall any big friendship lessons happening lately," Applejack thought aloud.
"Nor do I, things have actually been uneventful until that dreadful monster came and started the end of the world," Rarity shuddered, "Oh I can't imagine what all those poor souls he has absorbed are going through."
"And there's so much dark magic in the air, even the animals can feel it. The few I spoke to on the way here were either hiding or getting ready to go South to escape Equestria," Fluttershy whimpered.
"The more I look at it, the less I think the tree will be saving anyone. Doesn't something seem kinda off about it?" Rainbow hovered around the tree.
"It looks like it did when those vines were on it, like it's dying," Spike put a claw on the base of the trunk.
"The Tree of Harmony survives on friendship, love, and the like. With Erebus running rampant and absorbing everypony good magic is in short supply," Twilight landed at the entrance to the cave with a small saddlebag strapped to her side, "And Harmony is using most of her magic keeping him sealed."
"Twilight! What did you need to get that was so important?" Sunset asked. Without a word, Twilight opened her saddlebag and levitated a small necklace out for everypony to see.
"The Alicorn Amulet!" Rarity gasped.
"But ah thought Zecora locked that evil thing away?" Applejack said.
"She did, only she and I knew where it was. I actually hoped to destroy it one day once I figure out how, but desperate times."
"You're not actually thinking about using it, are you," Rainbow asked.
"The amulet is one of the most powerful artifacts in Equestria. When worn, it greatly enhances both power and control, it might allow me to finally use all the magic locked inside me. That might be enough to stop Erebus."
"Yes, but it also changes anypony who wears it. Trixie became something awful," Fluttershy cringed.
"Do you all trust me?" Twilight asked. They all answered yes. "Then I promise you that I won't let the amulet corrupt me. Nothing could ever make me hurt you and no amulet, magic or not, can make me into what Trixie became." Twilight turned and walked slowly to the entrance of the cave. "Now, I need you all to stay in here until it's over, I can't fight with everything I have if there's a risk of any of you getting hurt."
"Twilight!" Spike ran forward and hugged her, "Just be careful and come back, okay?" Twilight silently returned the hug, but didn't answer.
For the next few minutes, Twilight sat in the open ground outside the cave, her eyes were closed in concentration as she meditated, the amulet in her front hooves. The others watched from the cave.
"I can't let her do this, I have magic, I can help," Sunset started to go after her but Rarity put a hoof in the way.
"Wait dear, as much as I hate this Twilight was right, no magic you or I or any of us possess can do anything against that monster Erebus. You would just be in the way."
"I hate this, I feel so helpless," Rainbow looked anxious.
"If anypony can do this, it's Twilight, right?" Fluttershy looked uncertain despite her words.
The sky looked dark and empty, the world was silent as the ponies waited. Then, out of nowhere, he was there. There was no sign or sound to mark his coming, Erebus simply stepped out of the shadows under the trees. He wasn't enormous, he could be but he felt no need, so instead he was at his default size slightly larger than a griffin. He began walking on all fours towards the cave, almost casually, not even acknowledging Twilight, who was between him and the entrance. His mouth was twisted into a hideous grin and he drooled black saliva as he neared his goal.
"And so it is down to you and it is down to me. I will enjoy finally ending this Starchild, your magic, Harmony's magic, all magic, will be mine and I shall be truly free. Do you have any final words?" Erebus was a few yards from Twilight now. She opened her eyes and looked up at him
"Do you?" Twilight said, then in one quick movement she clasped the amulet around her neck. A second ticked by without anything happening. Gloom stood there staring at the amulet Twilight seemingly pulled out of nowhere as realization dawned on him. Then a violent explosion of magical power. What Twilight felt was indescribable, all her power was released and channeled through the amulet, moving on a will of it's own, the restraint spell broke as the amulet seized all of her magic and let it flow free. However, she felt no pain, her horn didn't crack and her fur did not burn despite the massive heat and energy she was generating. The amulet protected her even as it enhanced her already immeasurable stores of magic. She expected at least some pain but instead what she felt was almost pleasurable, was she always this strong? With power like this she could do anything. It was becoming difficult to think, as if she was in a red haze. Something whispered to her, egging her on. She could crush this so called god with one hoof, maybe even take his power for herse-NO! Twilight started, wondering who interrupted the whispers when she realized it was her own voice. What was she thinking?! Before she could fade back into that red haze she grabbed onto a mental image of all her friends, it was her anchor, a reminder of who she was and she would not let a piece of jewelry take it away. With her heart and soul filled with friendship, she was incorruptible. "Listen to me, I'm wearing you, I'm in control," Twilight forcefully whispered to the amulet through clenched teeth, her eyes bright white with power. Twilight woke up.
The first thing she saw was the blazing red aura around her body, swirling, fiery energy. The amulet was shining like a beacon on her neck. Her normally violet coat was dark crimson and her mane and tail were maroon flames with a dark purple streak running through them. She could see from the large trench dug into the ground and the line of broken trees and brush in front of her that Erebus had been hurled back when her energy had erupted. A burnt crater smoldered around her hooves. She turned to the cave, her friends were safe, but they backed away when she turned to them. What she didn't know was that her eye color had changed to a striking bright crimson and her gaze had an unsettling pierce to it. Spike stepped forward,"Twilight is that you?" She responded with a warm smile.
"Who else would it be Spike?" The ponies and dragon in the cave all exhaled in relief and visibly relaxed, then tensed up again as a roar echoed from somewhere in the forest. Erebus flew out of the brush like shadowy comet aimed at Twilight's back, impossibly fast to all, except Twilight. Her magic guided her as she kicked with her hind legs, catching Erebus in the face. Instead of shattering from the impact, her legs held, her body immovable as the magic flowed through her bones and muscles, pushing her body past its peak and beyond into the supernatural. Erebus shot up into the air, rocketing up and up into the clouds. A crimson blast from her horn launched him further into the atmosphere. Twilight followed, leaving a red trail as she soared into the sky. The two combatants breached the cloud layer.
Erebus stopped himself midair and rushed towards Twilight. As he flew he reached down into the clouds, at his touch they darkened. Lightning surged through the clouds and into his claws as the smell of ozone crackled in the air. With a wave he hurled a thunderbolt at Twilight. She blocked with a bubble shaped barrier and teleported, taking the now lightning charged barrier with her. With a flash she appeared above him and slammed into him, her shield cracking and sparking as it impacted. Erebus seized the bubble, his arms morphing into crystal swords to pierce it. Twilight vanished again and appeared below him, but he kicked downward, catching her in the face. Another barrier caught the brutal strike less than an inch from her face. Twilight plummeted down from the blow, falling into the clouds. As she fell, a pulse of magic erupted from her horn, freezing the water vapor in the clouds and hurling thousands of shards of hail at Erebus. He rushed through the stream of hail and tackled Twilight in a blitz attack. His razor claws seized her barrel, a thin barrier preventing them from gutting her. The heart pulsed, seeking to absorb her, but her fiery aura intensified, breaking his grip. In midair they twisted and tumbled as she evaded his grabs and swipes. Twilight's wings flapped frantically, trying to break out of the fall. Her horn was facing the wrong direction, she couldn't aim it at him properly. But it didn't matter, she fired anyway, the blast propelled her hoof first into him for an improvised kick/push off. Both were thrown in opposite directions. Erebus hurled several balls of dense, liquid shadow. The magic missiles flew towards Twilight as she performed a series of short range teleports and maneuvers to dodge, but they kept coming, gaining speed as they tracked her. Just before they could catch her, she summoned another bubble to stop them. Instead of being absorbed or deflected, the shadow stuck to the barrier, spreading across it and coating it to surround her. The shadow then contracted in an attempt to crush the bubble and Twilight with it. Thinking fast, Twilight teleported out of the collapsing bubble. The globs of shadow separated again and continued to pursue her. Twilight shot towards Erebus, flying as fast as she could, just before they would collide, she teleported and appeared behind him. Erebus turned to follow, but his own projectiles slammed into his back. While he was stunned, Twilight appeared above him and with a pulse of raw magic she charged. Twilight surrounded herself with a field of protective magic and entered a nosedive, tucking in her wings and spinning like a drill as she tackled Erebus horn first. Erebus fell down from the sky, a purple and red comet driving him down into the ground. A shockwave shook the Earth as they landed, the impact so great that it forced Erebus to spit up the Crystal Heart itself. Seeing her chance, Twilight grabbed it in her magic. With a mighty flap of her wings, Twilight flew upward and fired every ounce of magic she could muster down at her foe. The beam intensified and widened, blowing a hole deep down. When she finally stopped she realized that her attack had pierced the very crust of the world, causing the hole she had carved to fill with magma, burying Erebus somewhere way down below. Taking advantage of the opportunity, Twilight cast a spell of cold, turning all the released lava into rock. Twilight landed in the center of the hundred meter wide circle of black rock she had made. She needed to finish this. She touched her horn to the smooth igneous rock, muttering an incantation. A thin stream of energy left her horn and weaved down into the rock, seeping into cracks and spreading outward in a circle. The magic formed a large seal that spread across the filled crater, runes glowed and spun as Twilight whispered the words of binding she had learned from the writings of Starswirl himself. With a final word, the seal burned itself into the very rock, glowing white hot as it attempted to trap whatever was below it.
For several tense minutes, Twilight stared down at the ground, praying her seal would hold. Then the glow faded, the seal was now physically carved into the ground and Erebus was bound. Twilight relaxed, with the seal in place and the heart with her neither Erebus nor his puppet Gloom would be able to free themselves, it was over. She could see her friends in the distance, running over to where they saw her and Erebus fall. She floated the heart over to herself, it was terrible to behold, a dark sphere of concentrated evil, hard to believe that it was the same Crystal Heart. So many ponies trapped within, so many tortured souls powering it, the things that could be done with such power, the things she could do with such power. Twilight shuddered, she recast her suppression spell and took off the alicorn amulet, glad to be rid of the temptations it slipped into her thoughts. She looked at the two artifacts of dark magic before her, thankful that she had the magic of friendship to ward off the infinite opportunities for corruption sitting in front of her. She smiled as she heard her name being called by Spike and Sunset, it always amazed her at what she could accomplish when she fought for friendship. She still needed to find a way to free all those who were trapped in the heart and return it to normal, but she was sure that it could be done. She turned away from the evil trinkets to see her friends.
"Don't worry my friends, it's over."
"Yes, yes it is," Erebus whispered from behind her.