A/N: Just to clarify one thing, Dumbledore's power leaves Harry's in the dust.
[Harry]
Harry's eyes glowed alarmingly as he drew on more and more power. The air around the sphere of quartz warped further, the ground underneath it visibly cracking under the force of the young wizard's magic as it built higher and higher.
Harry snarled, waving his wand like an orchestra conductor as every single Transfiguration he had done before floated back up into the air, every spear and needle lengthening out into what looked to be several hundred lances of iron, all hovering menacingly around the Quintaped. The teen's efforts hadn't stopped there, the molten arena floor left behind by his predecessors flowed up and around the Quintaped like a snake, leaving a healthy gap but encircling it all the same.
The Quintaped barely noticed.
Rotating to face Harry, it pounced, leaping through the air with all the gracefulness of a bullet train: beautiful to look at from the side, deadly to be in front of. It dodged the snake of lava, smashed through the spears of iron like it had the ones of ice, and hurtled towards Harry.
Slowed by his own tiredness, Harry couldn't quite get his wand up in time.
The Quintaped slammed into the sphere of quartz, shoving it back and knocking Harry off of his feet, sending him tumbling into the back of his pocket of air. The stadium gasped as one as the boy collapsed in a heap, and the obvious sounds of the Quintaped gnawing through the quartz began.
He looked up, groggy, at the maw of the Quintaped, all five eyes focused on him with a beady intensity that would put revising-for-exams Hermione to shame. He could feel the transformation of the quartz breaking down around him, his sphere and sanctuary under attack from not only the Quintaped's mouth but also the rest of its body. The beast was already halfway through his defenses, and only a mere meter of pure quartz separated him from the gnashing teeth of the Quintaped –
[Judge's Table]
Only Igor's restraining hand on his shoulder and Olympe's hand on his arm kept him from intervening. Harry was quite clearly out of it, the knock to his head that the boy had suffered had no doubt left him woozy, and with every second the blasted magical creature grew closer and closer to the young boy he had always (privately) thought of as a grandson. Unable to help himself, and yet, still not in clear danger, thanks to the boy's own precautions. Albus muttered imprecations against this entire tournament, his fellow judges, his fellow lawmakers, and most of all himself, for allowing this tournament to place young Harry into such a predicament. Trapped inside a sphere of pure quartz, with a wall on one side and a slobbering, ravenous Class 5 magical beast on the other.
The stadium was rife with mutters of shock and pain, as the people in the stadiums seemed to be waking up to the thought that perhaps their boy hero would actually die, even if Albus would never let that happen. His own eyes began to flash as his power built, raw anger that he hadn't touched in fourteen years coming to the fore, since the last time he and Tom had clashed wands. Igor's hand slipped off of his shoulder like he had touched a live wire, and Albus knew there was only one reason Olympe could bear to continue holding on.
He looked down, eyes barely able to make out the shape of her lips as she mouthed the word "Calm" at him over and over, pure magical fury drowning out anything but –
It was like trying to hold onto a dragon. A rampaging dragon. Her hand bucked under the force of Albus' magic, and if not for her mother's giant blood running through her veins, Olympe knew she would've been thrown off as surely and easily as Igor had been. But heaven's help her, if an unleashed Albus Dumbledore let loose in the middle of a packed stadium, none of them would leave the Hogwarts grounds alive. Class 5 magical creatures were fought one on one, in the middle of desolate landscapes for a reason. The damn things were so strong and so intrinsically linked into magic itself that tearing them out was just about one of the most dangerous things a wizard could do. Little wonder that the last Nundu had been confronted by a force of one hundred wizards and only four had walked off with their lives.
If Albus didn't calm down –
[Harry's Subconscious]
Air. Water. Earth. Fire. Aether.
The four foundational elements and the one "extra" element. Many historians and philosophers and researchers and mad scientists had speculated on the nature of the fifth element. Some called it magic. Some called it divinity. Some called it the void between stars.
Harry? Harry didn't really know. He didn't know enough, hadn't done enough, hadn't seen enough. But when all else failed him, when his protections and spells and charms and wards and everything failed him. When even the pure foundational elements failed him. What was left?
[Harry]
Lightning. Magic. It boiled under his skin, across his eyes and through his breath. Lightning as Magic.
Baring his bloodied teeth in what even a charitable goblin would be hard pressed to call a smile, Harry called on his most formidable attack (and considering what he'd read, the stadium was lucky it wasn't the Dark freezing spell; the one that leaves seas frozen).
[Harry's Subconscious]
Pure magic was useless as an attack. Children were essentially the biggest conduits of pure magic, accidental magic that responded to great emotion. Young wizards and witches going through school could sometimes call upon the emotion needed, pure magic responding to their trauma. Adults could not.
But then again, adults didn't really call on metaphysical elements or beings, they normally had their wands and cast curses. Children were the ones with fairytales, with legends and myths and wonders. They could demand toys and treats and push away the weird stranger getting too close. Teenagers could fight back, briefly, but then they would run away, pure stubbornness giving way to fear.
Adults could always fight back.
Adults were, typically, not forced to face Class 5 magical creatures in the middle of a packed stadium baying for blood.
It's not Roman times anymore, you know.
[Judge's Table]
"I beseech thee."
Harry's first spoken words this whole event, and why did they snap Albus out of his fury, and send a shiver down his spine all at once?
"I beseech thee."
Albus paled, his earlier raging fury giving way to a sort of cold, bone deep fear. Internally, he prayed, prayed with everything he had, that not only had Harry not done what Albus thought he had, but that he was also not going to repeat himself again.
"I beseech thee."
Albus closed his eyes, weary beyond even his well-earned decades of life. Harry, good, noble, pure Harry, had picked up a chant. Where he had done so, and how, and why, were all set aside. He needed no help retaking his seat, as he and Olympe collapsed as one into their seats, Igor flopping down beside them. Bartemius and Ludo looked at them with wide eyes, taking in their ashen faces with fear, the unspoken question answered as the five of them, and the whole stadium at that, looked up as one into the suddenly pitch-black sky.
[Harry]
Harry giggled in the back of his mind. The Quintaped had shivered and stopped when he uttered the first line, had leaped away at the second, and was rapidly attempting to scuttle away with the third.
But it didn't matter anymore.
It wouldn't.
[Harry's Subconscious]
Chants were ingrained in magic since magic had been discovered. Centaurs and Veela had had chants of their own making centuries before humans existed or had knowledge of magic. Some of the more ritualistic magic in the modern age took their roots from the ancient chants, and most modern magic mirrored some form of chants in their entirety.
Chanting was the only way to call down truly destructive, and also truly constructive magic. In modern times they were regarded as something only dabbled in by dark wizards, as their constructive uses had fallen out of favor centuries before their destructive ones, and old rituals focused on enhancing an individual had only gotten more and more morbid in their quest to rip traits from noble creatures.
The original werewolves had not come from a disease, as many muggleborns thought, but rather from a cult of wizards gone mad with Moonlust after attempting to strip a Unicorn of its' speed and grace, resulting in a twisted form that granted speed and power, and the scorn of all their fellows.
The original vampires had resulted from one extraordinary coven of witches attempting to strip the High Elves of their everlasting beauty, and gaining only unnatural beauty and long life, but at the cost of being active only at night and being horrifying undead caricatures of humans and elves both.
[Harry]
He opened his arms, feeling the sky turn black as the chant progressed. A rule of three, for summoning me was the name of the chant, and it called on
Pure
Unchained
Lightning
A rip in reality tore through the sky, the weather going from a calm day to a howling thunderstorm in a split second, as the utter black heavens slowly pried apart at the edges, yellow hands made of gibbering madness and unchainable energy grasping as they tore at reality through the gap.
What could only be described by a sane person as madness leaped down from the slight opening, an insane mind would describe it as a slightly lopsided lion made from lightning, one side slightly larger than the other. It turned towards Harry, dipped its head, grabbed the Quintaped, and disappeared back up into the sky, the howling thunderstorm and pitch-black heavens returning abruptly to a calm afternoon with enough suddenness to drive a person mad.
Harry dropped his arms, feeling like he had repelled a thousand Dementors, and smiled. He was stronger now, and he would never run.