The next day everypony in both canterlot and ponyville was busy prepping for the invasion. Nearly half of the armed forces of the Crystal Empire had come to help. Civilians moved into various safe houses in the countryside that would be away from the fighting as canterlot’s army mobilized in the city and the town. All of Twilights friends, including Spike, Starlight Glimmer, Trixie and Sapphire Prism insisted that they stay with her in canterlot.

Outside the castle on the very mountain Canterlot was mounted upon, a shadowy hooded pony-figure with a dark black-and-red cloak silently made its way to the castle. It crept up a side of the castle walls and flicked out the retractable claws on one of its hoofs to silently attack an unsuspecting guard under the radar. It had been doing that for a while now and had made its way deep inside of the castle, silently using a crossbow to stun guards with darts and a complex grappling hook to attach them in between the roof supports of the high-roofed corridors to get them out of the way.

Using its Pegasus wings it made its way into the attic of the castle – reaching the part above the royal chamber where Twilight was discussing strategies with her elder brother and the newly reinstated commander Tempest Storm. It quietly removed a tile from the roof-drop to get a proper view and watched silently.

After listening and memorizing the most likely strategies, it pulled out its crossbow and fired a silent arrow in an arc-like manner towards the area directly behind Twilight’s vacant throne. The thing is, this arrow was tipped with a metal feather similar to the one Marble had used earlier. Except this one was a homing beacon to give somepony very dangerous a location to teleport to.

The masked Pegasus mercenary once again sat still and watched. The chaos that was about to unfold was not to be missed.

The three ponies were later joined by the rest of Twilight’s friends and received news that old Princesses themselves were en route. Celestia and Luna. They may be retired but they would not turn a blind eye toward the threat of a war. Tempest departed to give her instructions to the royal guard to safeguard the vulnerable parts of the castle – and to brief the soldiers as the temporary commander for the situation. Somehow nopony had noticed the foreign arrow behind twilight’s throne – and that it was flashing and buzzing with red lightning.

With an explosion of red lightning Twilight’s throne burst off its pedestal and flew across the hall over the heads of the surprised ponies, barricading the door with scary precision. They did not even have time to look towards the direction it flew from before they were forced on their knees and stunned with more red lightning – all except Twilight and Shining Armor, who gasped in shock at the two massive shadowy Alicorns who stood where her throne had once been.

“Who are you?” Twilight shouted instinctively, “What do you want?”

One of the Alicorns spread out its wings and floated towards her, landing with a metallic clang – at this point Twilight realized these were not regular Alicorns. Their entire bodies were made of what appeared to be strips of metal folded in a mosaic-like way to from alicorn-like figures. Their eyes glowed red and sparked red lightning, like the lightning that was crackling around their horns. They had no mouths yet appeared to be grinning evilly. The closer one bent its head down to twilight’s eye-level and snarled in a deep metallic voice as if it was wearing a mask.

“To end you.”

Twilight shot a powerful purple beam of magic from her horn in retaliation, but the metal alicorn simply took a step back absorbed it and responded as if it had been breathed on by a fly. It then gripped her in its red lightning and held her up to its own eye-level in a choke-hold. “If this is the best Equestria has to offer, you’re in trouble.” Then it used magic on her to shrink her back into how big she was back when she was just a normal pony’s height.

“Twily!” Shining armor shouted, only to be blasted with lightning from the other metal Alicorn and flung across the room. Somehow he retained his consciousness and muttered to himself that they were early and that they still had two days to prepare.

The second metal figure glared at him and said in a similar tone as its ally, “They have two more days, you do not.” Shining frowned in confusion, then his eyes widened in shock. “How could you be so stupid as to abandon your family and kingdom by taking half of your own army to aid in another’s war?”

Not giving Shining time to respond the door burst open as Twilight’s throne failed to do its current job and Tempest Shadow burst through, accompanied by the lord of chaos himself and a troop of royal guards. “Now.” Discord started, “I love a good and chaotic scuffle and all, but I’m going to have to ask you metal ponies to…” he paused when he saw Fluttershy’s slightly burnt and unconscious body on the ground. The room suddenly darkened as he gritted his teeth. “Now you’ve done it. NO ONE HURTS FLUTTERSHY!”

He charged at the metal Alicorn who was closest, who simply narrowed its eyes and flung a now unconscious twilight out of one of the large stained glass windows. Everypony gasped in shock, but Discord didn’t seem to care as he charged at the Alicorn with murderous intent. It reared itself up on its hind legs and struck discord down with a blinding blast of lightning so powerful that it flattened Discord onto the ground. “A lone Draconequus alpha. How useless. And siding with ponies! This is not why we spared you Discord.” Discord looked up at it with fury in his eyes.

“Then again, you don’t remember who you really are and what you really did to them… Let me change that.”

With a small spark of lightning it stunned Discord – then looked up at Tempest and her company of shocked royal guards. “Your reckoning is coming soon Equestrians, Citadel does not forget. We - The Iron Guard - will end you all!” And with a blast of lightning the second blew a hole in the roof and they both flew out of it. Tempest looked up to the hole and saw the smaller one near it from which the mercenary had been watching and eating popcorn the entire time. It stopped abruptly as it met her gaze and quickly replaced the panel in the roof. Tempest shouted to the shaken guard to wake up Rainbow Dash and give chase to the two metal Alicorns. She herself blasted past those standing behind her to pursue the mysterious masked Pegasus from the ground.

She did not stay hidden for long.

Tempest blasted the portion of roof directly in front of her. The surprised mercenary fell through, and quickly turned around, widened its gaze in surprise and continued to flee with renewed energy. It ran into two royal guards, who were coming from the opposite direction. The figure flipped out its claws and slashed their spears in two, then kicked both of them aside. This attack gave Tempest the opportunity to reach and tackle her, but the Pegasus used her hooves to send Tempest reeling over her just as she did. It got up and shot at Tempest with its crossbow, but Tempest darted her head aside and caught the arrow in her mouth, then crunched it with her eyes full of venom and her broken horn fuming with raw magic. The Pegasus immediately realized that it was lucky to still be conscious and quickly smashed through a nearby window to her right, descending to the rooftops of canterlot city and disappearing behind them.

Tempest hit the wall in anger as she had sprinted towards the broken window to watch her foe escape. Then she looked up to see a streak of rainbow zoom past her overhead followed by five clumsy and slow royal guard ponies pursue the already far-away so-called Iron Guards.

The two metal ponies ahead stopped and looked at their pursuers. “Can you handle them?” One asked the other.

“Oh please, I was always stronger than you Solar Flare.”

The other snorted and formed a white cauldron shaped portal lined with red lightning then disappeared through it, leaving the iron guard who had beaten Discord himself behind. He charged at the incoming rainbow streak with the intention to slice it in half, but rainbow dash was too quick for him. She darted aside and pounced on his head, leaving him startled for a second. The royal guards quickly caught up and pounded his head with their spears one at a time. “Ha!” rainbow shouted, “gonna have to do better than that clumsy!”

“My name.” the Metal Alicorn hissed, “is Black Abyss.”

He blasted one of the royal guards with red lightning, shot two other with a metal feather flung from either wing and punched the remaining two out of the sky with his metal hooves. They were too slow for him - Rainbow dash wasn’t. She continued to pounce and pummel his head, maddening him to a point of no return. No matter what tactic he used she always avoided it with her superior aerobatic skill, all while shouting belittling taunts to him. She stopped her assault, flying away from him and faced him directly as he shook his head for rebalance.

“Time to end this.” She said as she charged at him with a sonic rainboom. The metal Alicorn narrowed his eyes and hissed, “My thoughts exactly.”

This time he darted aside and bolted one of his blade-like wings upwards to slice Rainbow in half. She gasped as she tried to steer clear of it, but she was going too fast to do so on time. The bladed metal wing cut her left wing clean off, and she plummeted to the ground.

Twilight gasped in horror as she saw rainbow fall – having just recovered herself. “No!”

The iron guard’s eyes were bursting with glee and he made another cauldron-like portal and teleported away with a burst of red lightning.