AN: Thank you Goku275 and MDM11. MDM11, I don't know what the final pairing for Laxus will be in canon, and I don't really have anything planned for this story. Although, I would like to add that there is also the possibility of him ending up with the woman from 100 Year Quest (unnamed to avoid spoilers) who falls for him.
As Acnologia's spell descended upon the Dragons and dragon slayers (with Mest teleporting himself, Sherria, and Panther Lily to a safe distance), they shot into action.
"Physical abilities rise! Deus Eques!" chanted Wendy, strengthening all of her allies.
"Fire Dragon King's…"
"Iron Dragon's…"
"…Roar!" bellowed Natsu and Gajeel. Twin streams of flame and shrapnel collided with a section of the star-like lights, causing them to explode.
The three Dragons flew through the opening and toward Acnologia. The four dragon slayers, aided by their Exceed partners, followed behind. They all made it through the barrage unscathed — though the same could not be said for the town below, which was annihilated when the lights made contact and exploded.
The Black Dragon responded to his enemies' approach by raising his hand and firing three blasts of energy, each directed at a different one of the Dragons. Gajeel and Wendy protected themselves with Iron Dragon's Scales and Ile Armor respectively, pausing their advance to defend themselves.
Natsu, on the other hand, punched the energy blast aimed at him with a Fire Dragon King's Destruction Fist. He took a bit of damage when the spell exploded, but the Fairy was able to continue charging toward Acnologia.
"Fire Dragon King's Sword Horn!" yelled Natsu delivering a flaming headbutt to the Black Dragon's skull. He then shot away from Acnologia (who let out a groan of pain and brought a hand to his head) with a flap of his wings.
With the Fire Dragon out of the way, Gajeel and Wendy able to perform their own attacks the Black Dragon. They flew past Acnologia, striking him as they did so.
"Iron Dragon's Club!" roared Gajeel, smashing his transformed arm into the Black Dragon's limb.
"Sky Dragon's Wing Attack!" shouted Wendy, slamming an arm wrapped in a whirlwind into Acnologia's torso.
After recovering from the blows, the Black Dragon twisted to face the retreating Iron and Sky Dragons. Recognizing that the Fire Dragon was farther away, he inhaled in preparing to unleash a Roar upon the two.
But, Acnologia's spell was interrupted by a pair of attacks from an unexpected source.
"Poison Dragon's Fang Thrust!"
"Lightning Dragon's Roar!"
A snake-shaped blast of poison and stream of lightning struck the Black Dragon's side, causing his spell to dissipate as he lost focus. Acnologia turned to look at the source of the attacks and saw two dragon slayers supported by Exceeds. Both of them had the Dragon Force active.
"Don't you go forgetting about us just because we aren't Dragons," reprimanded Erik.
"Yeah," agreed Laxus, cracking his knuckles. "We're still powerful dragon slayer."
Acnologia looked at the two with a mixture of amusement and disdain. "Very well. Then I shall slay you first!"
The Black Dragon unleashed another Eternal Flare on the dragon slayers. It was smaller than the previous, which had turned most of Hargeon Town to rubble, but just as powerful.
Laxus and Erik tried to avoid the barrage, though they were clipped by the exploding blasts. Both mentally bemoaned the current situation, which was not ideal for them.
"With Happy flying me around, I can't turn into lightning," thought the Fairy, unwilling to abandon his temporary partner to Acnologia's spells.
"The voice of his heart… Why can't I hear it?" wondered the Independent Mage, troubled by the ineffectiveness of his Hearing Magic. "Is killing so normal to him that he doesn't even give it a second thought?"
The two shook off their concerns, choosing to focus on what they could do instead of what they couldn't. Laxus and Erik shot at Acnologia, preparing to attack.
"Lightning Dragon's Breakdown Fist!" shouted the Fairy. He threw a punch, producing a fist of electricity that shot at the Black Dragon. The spell struck Acnologia's arm and discharged, shocking the Black Dragon and briefly halting the limb's movement.
"Poison Dragon's Sharp Horn!" yelled the Independent Mage, striking the same spot on Acnologia that Laxus had. His hand, coated in poison, pierced the Black Dragon's already weakened scales and unleashed a toxic payload into Acnologia's body. In spite of this, the Black Dragon still looked unfazed.
"Fools!" bellowed Acnologia. "Do you understand now that your measly spells aren't strong enough to truly harm me?"
Happy flew above the Black Dragon and released Laxus, allowing the Fairy to descend toward Acnologia as he gathered the power for his next move. However, the Black Dragon moved upward and grabbed Laxus before he could perform an attack.
"Hook, line, and sinker," thought the Fairy, grinning. By holding back for his earlier spells, Laxus had successfully gotten Acnologia to lower his guard. Now, the Black Dragon wouldn't be able to avoid a heavy, point-blank attack.
Dark-red electricity crackled around the Fairy as he activated Red Lightning Dragon Mode. Too late, Acnologia noticed and realized that he had been tricked. The Black Dragon let out a gut-wrenching scream as all of Laxus's Magic Power was discharged into him in the form of red lightning.
As Acnologia dropped the Fairy, who was picked up by Happy and flown over to Sherria, Erik delivered his own final move.
"Poison Dragon's Twin Wings!" declared the Independent Mage, swinging his hand. Streams of poisonous gas shot from his fingertips as he did so, producing a cloud that enveloped the Black Dragon.
As this happened, Acnologia held his breath. Cautious after Laxus's trick, the Black Dragon didn't dare inhale the smog. Unfortunately for him, Erik's spell was just the set-up for the real attack.
"Fire Dragon King's Roar!" bellowed Natsu, unleashing a torrent of flames on Acnologia. As the spell hit, the poisonous gas was ignited, exploding and augmenting the blast.
Erik and Carla retreated, leaving the Fire Dragon to face the Black Dragon.
Acnologia screamed as the inferno consumed him. He closed his eyes and endured as the flames burned his body. Once the blaze died down, the Black Dragon reopened his eyes…
"Fire Dragon King's Grip Strike!"
…just in time to see Natsu's claw grab onto his face. The Fairy unleashed surge of flames on Acnologia, which again engulfed the Black Dragon.
"Bastaaaard!" roared Acnologia as the fire seared him. Ignoring the pain, he pointed his open hand out at Natsu and released a blast of destructive energy.
The attack hit the Fire Dragon dead-on, carving out a large chunk of his flesh and knocked him a good distance away. Wendy flew after Natsu, further reducing the number of enemies the Black Dragon had to deal with and giving him a moment of respite. That break did not last long, though.
"Dragon Slayer's Secret Art," began Gajeel, unwilling to give Acnologia the opportunity to recover. "Karma Demon: Iron God Sword!"
The Iron Dragon's right arm turned into a massive — even by the standards of Dragons — metal blade. He swung it at the Black Dragon, who reacted by catching the sword with his hand.
But that didn't stop Gajeel. The Fairy pushed against Acnologia's grip, trying to move the blade closer to the Black Dragon's body. Acnologia resisted, even as another of his enemies joined in.
"Dragon Slayer's Secret Art," yelled Sting as Lector flew him toward the Black Dragon. The dragon slayer had both the Dragon Force and White Fire Dragon Mode active. "Holy Supernova!"
Sting threw his fist forward as he approached Acnologia's head, the appendage coated in fire and light. The Black Dragon, his one arm already preoccupied, countered with a Roar. The two spells fought for dominance, producing another stalemate.
Ultimately, the deadlocks were broken when another dragon slayer took his opportunity to act. Rogue (and Frosch), Dragon Force and White Shadow Dragon Mode active, emerged from the shadows below Acnologia to deliver a strike to his unguarded body.
"White Shadow Dragon's Rough Silk!" shouted Rogue. String-like beams of darkness and light were released from his fingers, slicing into the Black Dragon's legs, torso, tail, and wings.
Because of the damage he received, the defenses that Acnologia had raised against Gajeel and Sting's attacks faltered. The sword of iron ended up cutting into his hand and his chest, leaving a sizable gash on both. As for the White Dragon Slayer's fist, it smashed into his face with enough power to break scales and leave burns.
"Raaaaaaaaah!"
Rather than cry in pain, the Black Dragon responded to the three-person assault by letting out a furious, feral scream. Up until now, he had been keeping his rage in check. But the concerted efforts of his enemies had made Acnologia feel cornered for the first time in over a century, something that rapidly wore away at his patience until it finally snapped.
Now, there was nothing restraining the Black Dragon of the Apocalypse's wrath.
"Diiiiiie!" screamed Acnologia, charging his limbs with destructive energy as he attacked Gajeel. The Black Dragon spiked the Fairy into the ruins of Hargeon Town, then assaulted him in a wild manner. Fists, claws, feet, and even tail… Acnologia threw all of it at the Iron Dragon.
Unable to predict how he would be hit next, Gajeel was forced to simple endure the barrage of attacks. The Fairy used Iron Dragon's Scales to strength his defense, and even that only softened the ferocious blows.
Sting and Rogue tried to help their guildmate, raining spell after spell down on the Black Dragon. Yet Acnologia simply ignored them, fixated on killing the only other Dragon present.
Eventually, the dragon slayers ran out of Magic Power. They collapsed from exhaustion and had to be taken away by Lector and Frosch, leaving Gajeel to continue serving as the Black Dragon's personal punching bag. It wasn't too much later before the Fairy finally gave out, knocked unconscious when the accumulated damage caused his Iron Dragon's Scales to fail.
With his enemy down, Acnologia inhaled, preparing to end Gajeel's life with a Roar. Fortunately for the Iron Dragon, the time he had bought with his resilience proved to be enough to save his life.
"Lightning Sky Dragon's Roar!"
A blast resembling electrified tornado struck the Black Dragon from his left side, knocking him away from the downed Fairy.
"I won't let you hurt my friends anymore!" declared Wendy, Lightning Sky Dragon Mode active. "It's my turn to fight you now!"
Acnologia got to his feet, shaking off the Fairy's attack. He then opened his mouth, firing a Roar at the Sky Dragon.
"Ile Vernier," chanted Wendy, raising her speed as she avoided the Black Dragon's spell. She shot toward Acnologia, striking him with a claw covered in wind and electricity. "Sky Dragon's Crushing Fang!"
The Black Dragon howled in pain, then tried to retaliate with a swing of his own magically-enhancing claw. Wendy ducked the blow and delivered another attack.
"Lightning Sky Dragon's Wave Wind!" yelled the Sky Dragon, producing an electrified tornado from underneath Acnologia. The whirlwind spun the Black Dragon around as it shot him into the air, disorienting him.
"Raaah!" snarled Acnologia, fighting against dizziness and the sting of electricity to reorient himself. He recovered after a few seconds, just in time for Wendy's next spell.
"Ile Arms," spoke Wendy, boosting her attack as her hands started to glow. An electrified barrier of wind surrounded the two Dragons, cutting off the possibility of escape. "Dragon Slayer's Secret Art: Shattering Lightning: Sky Drill!"
From the Fairy's hands shot a stream of wind and lightning. The spell struck Acnologia in his chest, obliterating all of the scales covering it and exposing his bloody flesh as the force behind the attack shot the Black Dragon even higher into the sky.
However, despite the damage he suffered, Acnologia remained conscious. A few seconds after the spell faded and he started to fall, the Black Dragon began to flap his wings until he hovered in place. Then, he unleashed his own spell on Wendy.
"Eternal Flare!" bellowed Acnologia, again firing the attack that had ravaged Hargeon Town. Except, this time the barrage was concentrated on the Sky Dragon instead of being spread out over a wide area. Having just used her most powerful attack, Wendy couldn't muster the strength to escape Eternal Flare's range and was bombarded by it.
When the smoke cleared the Sky Dragon was laying on the ground, covered in heavy wounds and surrounded by craters. On the edge of consciousness, she used the last of her strength to utter two words.
"Ile… Arms…"
As the Enchantment activated, Acnologia finally took notice of its recipient — Natsu Dragneel, who currently had an enormous amount of Magic Power gathered in his open mouth.
When Wendy was healing Natsu, the Fire Dragon came up with an idea to defeat Acnologia. They would use all of the remaining Magic Power from Meredy's Maguilty Sense to perform one supercharged spell, adding in an Enchantment from the Sky Dragon for good measure.
"Dragon Slayer's Secret Art…" uttered Natsu.
Having released some of his wrath on the two Dragons and dragon slayers, Acnologia had calmed down enough to regain some of his senses. And, as the Black Dragon looked at the last remaining Fairy and the immense energy that he was concentrating into his mouth, those senses screamed at Acnologia to fly away as far and as soon as possible.
"Run! Run! Ru—!" thought the Black Dragon, attempting to escape imminent death. But, as he turned to flee, a feeling of vertigo overwhelmed him. It took Acnologia all of his focus just to keep from crashing into the ground. "What… urgh… is this?"
The answer to the Black Dragon's question was poison. More specifically, the poison that Erik had injected into Acnologia with Poison Dragon's Sharp Horn. The dragon slayer had funneled most of his Magic Power into the spell, allowing it to eventually overcome the resilient body that the Black Dragon had developed from slaying countless dragons.
"…Fire Dragon King's Kaleidoscopic Roar!" screamed Natsu, breathing flames that were colored like a rainbow due to all of the different people who had contribute their Magic Power to the spell.
The inferno swallowed Acnologia whole. The Black Dragon attempted to eat the rainbow flames, only for them to instead devour him from the inside. In less than a minute, Acnologia was completely immolated, reduced to nothing but ash that scattered in the wind as the fire faded away.
"It's over," said Natsu. He thought about the others. If it hadn't been for them wearing away at and stalling the Black Dragon while Natsu prepared his final attack, slaying Acnologia never would have been possible. The Fairy broke out into a huge grin. "We won!"
It was time to go back home.
Omake
"It's over," said Blaze, to which Iggy nodded in agreement. She, Iggy, Asuka, Alzack, Bisca, and Porlyusica were currently on the outskirts of Magnolia Town. After Universe One ended, they found themselves at the former site of Fairy Tail's second guild hall. "They won!"
Despite the fact that all five of them had provided Magic Power through Meredy's Maguilty Sense, there was no way for any of them to know how the battle had turned out now that the Independent Mage's spell had ended.
And yet, in their hearts, the Dragneel kids could tell that their dad and everyone else had won. The two of them and Asuka began to celebrate the end of the war, cheering and dancing as the adults looked on with warm smiles.
AN: I wasn't sure if this battle would take one or two chapters but, now that I've written it into one that's somewhat longer than usual (possibly the longest), I can confidently say that the next chapter will be the last.
Two things that weren't mentioned in the chapter: 1. Sherria didn't heal Natsu because she was busy with Laxus, Erik, Happy, and Carla. 2. The reason Sting and Rogue ran out of Magic Power despite the Maguilty Sense stockpile was because it was already being funneled into Natsu's final attack.
By the way, I feel really good about this fight. Everyone contributed, either inflicting significant damage on Acnologia or buying time for the final attack. As for the attack itself, compared to Natsu's earlier fire that equaled Igneel's and defeated Zeref, this flame surpassed those of the Fire Dragon King. My only regret is that it feels a bit like Gajeel, Sting, and Rogue had to share the spotlight instead of getting their own moments to shine.
That is all. Goodbye for now!