"Twilight no..." Muttered Cadance sadly.

A stunned silence filled the room, only to be broken by Twilight, "What? Not happy to see me? You disappoint me Celestia, was I not your star student? And you Pinkemena Diane Pie, I thought you liked surprises?".

"Only fun ones..." muttered Pinkie, her mane deflating at the use of her full name.

Celestia shook off the sense of shock and addressed Twilight once more, "Princess Twilight, why are you doing this? Practicing dark magic and then luring us out here? This is unlike you."

Twilight grimaced with annoyance, "Shows how much you knew princess", she got up off her throne and took a step towards the group, "Long story short, in that ruin I found many great things, but among all of them there was one in particular that interested me, a box, that box showed me Equestria's future if it were to remain under your, heh, 'enlightened' rule".

Luna's eyes widened as realisation came to her, "Twilight, listen to me! That box..."

"QUIET!" shouted Twilight with a stamp of her hoof. "Destruction is what the box showed, a power will come to threaten us, and only a single ruler with the willingness to build a new Equestria over the ruins of the old, to do whatever it takes to protect the things they, I love...", Twilight glanced away from the group for a moment unable to make eye contact, but quickly regained her composure, "Only a ruler like that can save Equestria, and that ruler will be, and must be, ME!". Twilight closed her eyes and took a deep breath, tears began to swell up in the eyes of the mane 5 and princess Cadance, only Luna and Celestia were able to stay seemingly calm. They all began to notice shadowy figures entering through the side doors, several shadow ponies began to pour into the room. Twilight herself began to glow as a bright ball of energy coloured both black and a dark purple began to form around her, completely enveloping her, suddenly the energy exploded outwards as Luna noted the similarities to her own transformation into Nightmare Moon, Twilight was using the same, or at least a similar spell to change herself also. The energy dispersed and Twilight came back into view.

Twilight was visibly taller, about the size of Celestia, her mane and tail were beautifully flowing, a mix of dark purple and a darker pink, with what seemed to be stars twinkling here and there. Her fur had also darkened significantly, almost black but a purple tinge was still noticeable, her eyes had stopped glowing green, but a green aura did still emanate for the sides of her eyes, her pupils were now black slits and her iris was a shade of red. Her horn had also elongated and her cutie mark, while the design remained the same, the inner star had turned from a bright purple to a dull grey while the outer stars had turned to the inner stars original purple. Her armour and crown remained largely the same, but had adjusted to fit her new form. Nightmare Twilight outstretched her almost black wings and took off into the air, blasting a hole into the roof with a magical blast from her horn, she began to hover just beyond the hole and turned to look at the group once more, awaiting her first challenger.

The shadows began to close in on the group, Celestia turned to them. "Ok, new plan. Luna, Cadance stay with the others and help fend off these creatures, I will attempt to subdue Twilight, I just hope she can see what she is doing is wrong before we are forced to banish her, or... worse".

The group nodded, Cadance and the mane 5 wiped away their tears and with Luna turned to face their adversaries. Celestia turned to face Nightmare Twilight and took to the air, exiting through the hole and coming face to face with her.

"Twilight, please stop this, think about you friends, everything you have been through with them, is this how you want all that to end?" pleaded Celestia.

"I'm doing this FOR THEM, they are more likely to survive in the new Equestria than under the weak minded rule of you three! If a 'few' freedoms are abolished in the process then so be it. Once day you will understand...". Nightmare Twilights horn glowed a bright green as she charged a strong spell, which she unleashed with great force towards Celestia, who dodged it with ease and grace. Nightmare Twilight unleashed several more and Celestia dodged them all, but with each attack getting closer and closer to their target.

---

In the throne room the whole castle shook as several spells hit it. Fluttershy was staying back as Rarity, Cadance and Luna were using their spells to cover Applejack, Pinkie (who's mane had re-inflated, and she had also conjured a party cannon from seemingly nowhere) and Rainbow Dash who were laying into the shadow ponies who, while they hit quite hard, being made of shadow were quite fragile themselves and dissipated easily. The problem was there was seemingly no end to them and they couldn't keep fighting forever.

Rarity addressed Luna, "I simply don't understand why Twilight didn't come to us about this future, why do all this to prevent something we ourselves perhaps could have prevented together?".

"Fear" replied Luna, "Fear has corrupted Twilights mind and led her to dark magic, fear can be even more corrupting than the jealousy I once harboured, but this isn't entirely Twilights fault, the box is not what it seemed to be, I'll explain when we aren't being attacked, but suffice to say don't lose faith in Princess Twilight just yet".

"I haven't" said Cadance with determination.

---

A green flash of light flashed across Celestia's face as she narrowly dodged the latest attack. Celestia was slowing and knew she would soon have to retaliate. So with a heavy heart and with a tear sliding down here face Celestia charged her horn and let off a dazzlingly powerful yellow coloured spell towards Nightmare Twilight. The sudden attack caught Twilight off guard and she was flung far backwards as the spell made contact with her chest. Nightmare Twilight fell out of control through the air, but with effort she managed to steady herself. Celestia charged a second attack and sent it barrelling towards the corrupted pony, but she was just able to counter with a spell of her own, their spells connected and clashed violently, with Celestia's immediately gaining ground on Nightmare Twilights.

On the ground a large portion of the shadow ponies stopped and deformed into a shadowy mist, they then flew into the air towards Nightmare Twilight, who began to absorb them, adding their strength to hers. With this new found power Nightmare Twilight began to push back against Celestia's spell with more force, her horn began to pulsate and spark as her spells intensity increased. Celestia's eyes widened in panic as her spell lost ground, she realised she would lose the duel and attempted to pull out, with nothing to stop it Nightmare Twilights spell jolted towards Celestia with renewed force, Celestia went to dodge but the wicked green spell just skimmed her, sending Celestia into a plummet, crash landing onto the crystal roof of the castle. On the ground Luna and Cadance saw Celestia's injury and, with the mane 5 saying they will be fine with the now greatly thinned number of shadow ponies, took to the skies and both began to fire at Nightmare Twilight to distract her from the injured Celestia. Celestia looked up at the battle, and began to sob, not because of the pain she was in, but for how far her star student, her friend had fallen.

---

Rainbow Dash looked up at the fight in the sky, and saw the two sides currently equally matched, Nightmare Twilight had the most individual power but Luna and Cadance's combined power and teamwork was giving Nightmare Twilight a run for her money. Dash turned to the others, "Everypony! I'm going up there to help the princesses!".

Applejack stopped and turned to look at Rainbow Dash, "Shoot Rainbow this ain't the time for heroics, now come on we almost got em' beat".

Dash shook her head in refusal "They're in a stalemate up there, but all they need is one more pony to lend a hoof and we get the advantage!". Dash zoomed up towards the fight before Applejack could stop her. She sped straight towards Nightmare Twilight.

Cadance saw her and screamed "Rainbow, don't!"

True to form Rainbow Dash ignored her and kept going, intending to tackle Nightmare Twilight, who saw Dash coming, and tackled her first, both plummeting straight into the castle roof nearby to Celestia. Dash lay on her back, pinned by Nightmare Twilight who had one hoof on Dash's chest. Dash squirmed to try and free herself, to no avail as Nightmare Twilight just pinned her down with increased force when Dash tried. Nightmare Twilights horn began to charge as Celestia looked on in horror, unable to help. Nightmare Twilight and Rainbow Dash's eyes met, Dash's began to fill with tears as she realised she was staring up into her own friends face, a friend who was about to end her.

"Twilight..." Dash choked out between sobs, their eye contact not breaking.

Twilights eyes widened and her horn stopped charging as her grip on Dash lessened. Celestia looked on, thinking that, maybe, just maybe the friendship between Dash and Twilight still existed somewhere in Nightmare Twilights heart. Twilight stepped backwards off of Rainbow Dash, they sat there just staring for a good moment before the peace was shattered by Luna tackling Nightmare Twilight, who promptly blasted Luna off. Nightmare Twilight got back on to her hooves and stood up, Cadance and Luna stood metres away, Celestia mustered enough strength to also get back up and stood in formation with the other princesses. Nightmare Twilight was now heavily outnumbered but the three princesses were all either exhausted by this point or injured, the outcome of the following fight was uncertain to all. Nightmare Twilight began to charge for another attack, but then quickly de-charged and began to chuckle sinisterly.

She addressed the princesses, "This is a nice show your putting on, but what's the fun in ending you three here and now? I want you to see what will happen to your precious inferior Equestria for the new one to be built, but where should the demonstration be? Oh, I know the perfect place, see you at Ponyville!" Nightmare Twilight laughed evilly as she teleported away before anypony could stop her.

Applejack and the others had finished off the last of the shadow ponies as Celestia, Luna, Cadance and Rainbow Dash flew down to re-join them. Applejack examined the group, "Where is Twilight?" she asked.

Celestia looked at Applejack and said, "Gone, to Ponyville, and I fear what her intentions may be for the town. We are going to have to hurry back there before it is too late to save it, I fear Twilight may be lost to us now".

Luna piped up at that last part, "No, she isn't lost, if I could be redeemed then so can she".

"But we used the elements of harmony to defeat you, and we don't exactly have those anymore" said Rainbow Dash.

Luna scanned the group, "No, but we have something better, her friends", Luna sighed, "Besides, that box that showed Twilight that dark future, I now know where I had seen it before, when I was Nightmare Moon I researched many dark artefacts, one was simply called 'the box of fiendish lies', it was designed by King Sombra to show you something horrible, something to shatter the foundations of your core beliefs, in Twilights case the belief that the power of friendship could protect Equestria, the future Twilight saw was a fabrication of the box, nothing more".

Celestia considered this, would Twilight believe them if they told her the truth? And then there was that whole thing with Rainbow Dash on the roof, yes, Twilight does still exist under all that dark magic, "We will save princess Twilight, from herself" proclaimed Celestia to the group.

---

In Ponyville daily life was continuing as normal, as Applebloom stood in front if the town hall with the Sweetiebell and Scootaloo concocting their next scheme to get their cutie marks, she noticed a shadowy figure in the sky flying fast towards them. The figure looked familiar somehow.

"What are you looking at?" asked Scootaloo.

Applebloom stepped forwards and squinted her eyes, "Twilight?".

Say tuned for the conclusion...