Discord had made the Death Egg his new throne room, sitting quite comfortably as two Egg Pawns brought him lunch: a chilidog. He grabbed it before gobbling it down in one bite and laughing to himself.
"Hahahahaha! Never before have I felt so alive! If I know Sonic, he'd risk his life to go through that wormhole I set up for him and try to survive all those challenges I so cleverly left for him! He'd be lucky to actually make it here in one piece!" He said before rising to the...air and pacing around. "Not only that but as I steal the energy from Dr. Poached Egg-man's machine, I feel myself getting stronger and stronger by the second! Soon Equestria will be mine once again! And maybe even perhaps Sonic's world is up for grabs! OH I looove being evil!" he said.
"I'd be fine if you were just after Equestria, but now you want mobius too? That's a bit greedy if you ask me!" Sonic said.
Discord did a double take, noticing Sonic the Hedgehog and The Mane 6 just a few feet away from him. "SONIC?! How are you still alive? I put everything into building that wormhole just for you and now you just made it harder for me to take over Equestria! But then again, I am impressed you've made it this far! I can see why Egghead hates you so much!" he said, rubbing his instant mustache
Twilight frowned. "One last chance Discord! Surrender or we'll make you surrender!" she warned before pulling out her crown and the rest of the girls readying their necklaces.
Discord laughed as he pulled off the fake mustache and tossing it elsewhere. "You have no idea what you're up against! You're the ones who had better surrender!" Suddenly, Discord began to emanate a sinister dark aura as he began to grow bigger and bigger and bigger until he broke right through the Death Egg's nearly indestructible metal, exposing the interior to the cold depths of space.
Sonic and the Mane 6 quickly supercharged themselves once more before zooming off into the final battle against Discord and this time, failure was not an option.
(Final Boss: Discord)
(Phase 1)
Thanks to the power of the Chaos Emeralds, Sonic and the girls were unaffected by the vacuum of space, zooming around freely and aiming for the perfect opening to strike.
"Alright Godzilla, time to take you down once and for all!" Sonic exclaimed.
Discord grinned evilly, thinking of Super Sonic as a joke. "I'd love to see you try Hedgehog!" he roared before firing multiple shots of energy from his paw/talon.
Sonic dodged the shots with ease before freezing, feeling Princess Celestia trying to reach both him and the girls. [Sonic! Girls! Discord is…power from the emer…small weak point...be careful he's going to…] The transmission, barely incoherent, was abruptly cut off.
Discord resumed attacking with powerful slashes from both hands. Sonic and Twilight were both hit, sent scattering before recovering and getting back into position. At this point, Discord needed a moment to recharge, leaving Sonic and the girls to rocket into the draconequus' body.
Discord grunted with pain but shook it off. "Grah! I was just warming up! Now i'm really gonna bring the heat!" he said. Discord took a deep breath and exhaled hard, breathing an intense blast of fire. All the girls were forced backwards except for Pinkie who seemed to be unaffected by Discord's attack.
Rarity noticed this and grinned. "Twilight! For every one of Discord's attacks, one of us are somehow immune to it! Could we use that as some kind of opening?" she wondered.
Twilight thought for a bit. "Only one way to find out! Sonic, We'll whittle him down while you wait for an opening!" explained the golden alicorn.
Sonic nodded and gave a thumbs up. "Roger that!" he said.
(Phase 2)
Twilight and the girls charged forward as Discord fought back with another breath of flames. The girls quickly dodged out of the way except for Pinkie who just kept going until striking the draconequus with full force. "Take this!"
As Discord recovered from the sharp pain, Sonic slammed into him hard. "Here goes nothing!" he exclaimed right before impact.
Twilight smiled. "It's working! Keep it up everypony!" she encouraged.
Discord growled before pointing a finger at the group, shooting a laser at them. Twilight made it through and slammed right into the draconequus. As Discord reeled back in pain, Sonic boosted into his stomach!
(Phase 3)
The god of chaos roared in anger. "That's it! I'm through playing your stupid games! Chaos…" Discord began to summon every bit of strength left in his body.
Twilight and the girls assumed formation once more with Sonic joining them in the center. Their elements began to glow brightly, drawing power from the girls' spirits.
"Here we go!" exclaimed the golden hedgehog before grabbing Twilight's hoof and pulling her along with the rest of the girls into the blast of harmonic energy. Now the ponies were actually part of the blast as well as Sonic.
Discord finally fired. "BLAST!"
Once again, it was a struggle to overpower one another and Discord was winning.
Sonic grunted as he began to feel a power he never felt before...a harmonic surge of energy raced through his body. Sonic's eyes began to turn from red to magenta. His golden color got brighter and brighter until it reached a heavenly white! His stomach, glove cuffs and sock cuffs changed colors to match one of the elements of harmony and a marking similar to Twilight's cutie mark appeared on his forehead.
Super Sonic had transformed into HARMONIC SONIC!
The sudden supercharge filled Sonic with power. His multi-colored areas began to take on Applejack's elemental color. Sonic was now plowing right through Discord's attack.
The draconequus struggled to hold them back with all his attacks put into one energy beam but it was no use. Sonic and the girls broke right through before delivering the final blow.
"RAH!"
Discord was hit by Harmonic Sonic with incredible force. The harmonic blast engulfed him and began to revert him back into his normal-sized, stone statue self. "Noooooo!" he screamed as the stiffness rose from his legs to his head before he vanished back to Equestria...leaving Sonic alone to shift back into his normal form…and everything went white.