"NOW!"
Oleandra's voice rang throughout the tower, echoing off the stone walls as, for a few breathless seconds, it seemed nothing would happen… and then every candle in the chandeliers hanging high above went out at once. Were it not for the brilliant golden glow radiating from the Sword of Promised Victory held aloft over Loki's head, the Grand Staircase would have been swallowed by darkness, but nobody was paying any attention to the castle's lightning.
Hogwarts itself audibly groaned as it shook to its very foundations.
In the span of a heartbeat, the telluric might of the planet's core, sealed within the silver orb buried beneath Hogwarts, surged through the castle's plumbing. From one end of the ancient stronghold to the other, toilets and sinks erupted in geysers of pressurised water, and where no outlet could be found for the excess pressure, the pipes simply burst apart, flooding each of the castle's floors.
Oleandra cried out, clutching her face as the sheer density of magic in the air seared her Mystic Eyes. Even through closed lids, it felt as though she were staring into a supernova from only a few feet away… and then, as suddenly as it had come, the pain ebbed, and her ordinary sight returned.
"What… what have you done!?" Loki shouted in fear. "What is this!?"
One by one, the runes etched into his host's soul were being washed away; his hold on the boy called Draco Malfoy was slipping. He could not fathom what trick the Greengrass girl had wrought; what was happening to him was supposed to be impossible.
In ten thousand years, Odin's soul-possession magic had never once failed after fully taking hold. Even if Loki remained in seclusion in the deepest caverns of the earth, bereft of blessed starlight for a hundred years, that still would not have undone the soul engraving… and yet here he was, bathed in the starfires' baleful glow as he stood beneath an open window, far above the ground on the seventh floor, and Odin's ancient magic was still unravelling.
"ANSWER ME!!" Loki screamed, raising Excalibur even higher. "OLEANDRA GREENGRASS!!"
Draco's body blurred, looking as though he were splitting into two; two bodies overlapping, yet not quite aligned, creating the uncanny illusion that he was vibrating slowly apart.
"Like father, like son, eh?" Oleandra sniggered, even as blood streamed down her cheeks from her eyes. "You Asgardians certainly like setting yourselves up to be hoisted by your own petards. Look up, and you'll understand!"
Loki looked up at the sword above his head, his eyes widening in disbelief. Excalibur was drinking in the dense telluric magic that coursed through the Grand Staircase Tower… using his own body as a conduit to draw in the planet's raw power, just like a wand would.
Without the sword in his grasp, forcefully channelling the magic of earth and moon through his very being, the light of the runes etched upon his soul would merely have been extinguished for as long as the telluric energy suffused the ambient atmosphere, rather than being utterly annihilated as it now was.
No wonder the Felix Felicis had urged Oleandra to wait!
Had she played her trump card from the start, before Loki produced Excalibur, she would merely have disabled his runic magic. Facing an old monster with ten thousand years of cunning and experience, the battle would have been fiercely contested, all the more so since she would also have been equally deprived of runic magic, the strongest weapon in her arsenal.
"The bane of the stars…" Loki groaned. "Ogham and Futhark, the antithesis…! To think those weak carvings could produce such powerful magic…!"
As someone born ten thousand years ago, back when the terror of Faeriekind had still been fresh in the inhabitants of the British Isles' minds, Loki had thought himself well versed in the lore of Faeries. They constantly played tricks with humans, taking the things most precious from them… but magic goes both ways. He knew that if one could trick the Fae and perform a counter-ritual, they could reverse their magic and take things from them!
Loki had fooled Oleandra into believing that Ginny had pushed Daphne down the Grand Staircase, even though his true intention had been to turn her against Astoria, and through that deceit, he had gained the right to claim something from her… and he knew exactly what he wanted.
Fifteen hundred years ago, Loki had watched the tragedy of King Arthur and the fall of the Round Table unfold from the constellations above. After Arthur and Mordred fell by each other's hand, Sir Bedivere returned Excalibur to the lake, placing it once more in the Lady of the Lake's safekeeping… and that made the greatest weapon in the world the perfect prize for him to steal from the Lady's current incarnation, who hadn't even realised she had the damn thing.
"This is your just desserts, Loki!" Oleandra shouted. "You shouldn't have stolen that sword!"
The artefacts the Fairies had crafted were masterworks capable of making their chosen champion invincible in combat, so long as they held both scabbard and sword. The scabbard, named Avalon after the Fairies' island, made one invulnerable to all Muggle weapons and impervious to all Wizarding magic, and the sword, named Excalibur, was capable of untold destruction.
The forging of Excalibur marked the only time the selfish Great Fairies of Avalon, the first-born of the planet Earth, set aside their quarrels to work together for a single purpose. As children of the Earth, they had naturally wrought its enchantments with scarlet Ogham, runes bound with the power of earth steeped in the blood of a thousand battlefields and of the crimson moon that watched from the night sky.
Excalibur had been forged to drive back the invading Saxons, who had crossed the sea with the star-born magic they had inherited from the Aesir. How could such a blade ever promise victory to one such as Loki? Whose heart was far from pure? Whose father had banished Avalon halfway between Niflheim and Midgard? Whose descendants would wage war against Britannia for a thousand years to come?
There was no way he could properly wield Excalibur's power!
Loki desperately tried to let go of the sword's golden hilt, but his fingers would not obey him. Golden light suffused Draco's body, cleansing and purifying the darkness parasitising his soul with golden flame, even as Loki continued ranting and cursing Oleandra's name, until only a single word remained on the tip of his tongue…
"Excalibur..." Loki breathed.
The aura cloaking Excalibur's blade erupted skywards, a torrent of golden light blasting through the Grand Staircase's ceiling with a thunderous roar. For a few breathless moments there was only blinding brilliance, and then the tower's spire and roof began to crumble inwards, sending shattered beams of wood, twisted metal fittings, stone blocks and broken slates tumbling down the tower after Draco Malfoy's limp body as it fell, dragging the magical staircases crashing down with them.
The teachers, having finally elbowed their way through the crowd, raised their wands as one.
"ARRESTO MOMENTUM!"