Repairing the cracked floor of the Map Chamber proved hardly a challenge for Oleandra. The room's proximity to the castle's nexus of power ensured it had priority access to the telluric energy drawn from the ley lines; in fact, by the time Oleandra cast her Mending Charm, the fissure had already begun to heal itself.
In no time, the basin at the centre of the room was restored, filled once more with the silvery fluid into which Oleandra had landed feet first when she had first Apparated into the room.
"Now, just watch," Percival Rackham said. "Then you'll understand why this place is called the Map Chamber!"
"I'm watching," Oleandra said drily.
The pool of silvery liquid shimmered, and twinkling lights appeared across the silvery expanse, as if some invisible hand had suddenly lit a myriad candles beneath its surface. The liquid rippled, but the tiny dots of light remained constant, unperturbed by the troubled waters.
"This… is a map," Oleandra said, stating the obvious. "It really is a Map Chamber…"
In places, the diaphanous silver bubbled and rose higher and higher, forming hills and buildings, and in others, it sank, creating valleys, rivers and lakes.
"I told you so," Percival said smugly, stroking his ratty beard.
As the ripples spread, more details added themselves to the map. The silvery liquid would swell into small peaks, then recede, leaving behind intricate constructs. Before long, a small replica of Hogwarts Castle and the grounds lay at her feet, and still the ripples continued to propagate concentrically, reproducing the surrounding area in great detail.
"What's this?" Oleandra murmured. "It almost looks like…"
Hints of scarlet red glowed amongst the sea of silver, tracing an intricate pentagram that encompassed the entire castle grounds. These weren't Oleandra's star runes, which could shine in any colour of the rainbow when lit; Ogham runes glowed only scarlet or crimson, symbolising the unbreakable blood ties that bound the Earth to the Moon.
"As former Headmistress, I can take over the explanations from here," said Niamh. "The Map Chamber is where the Headmasters go to make alterations to Hogwarts's rules. For instance, as you can see around the outer perimeter—" she gestured vaguely towards the castle miniature below from her portrait, "—Professor Dumbledore added extra restrictions over the grounds to temporarily prevent broomstick flight… it was about four years ago, I believe."
Oleandra remembered the panic that had gripped the castle when Sirius Black escaped from Azkaban and repeatedly invaded Hogwarts while evading Auror pursuit. One single Death Eater on the loose, to think that was considered a crisis back then… times had certainly changed.
"Ah, and if you look here, you'll notice that the Anti-Apparition Jinx that covers the entire area is usually lifted in the Great Hall for a handful of days in January," she added. "But you must have already known that, seeing as Apparition is the only way to enter this place."
Oleandra had never made it past December of the previous year, so she'd missed her Apparition lessons and the chance to get her licence. Thankfully, Mai had helped her with that, catching a Diricawl for her to steal its teleporting prowess from.
"It takes years of specialised study in ancient runes to modify the existing wards and restrictions," Niamh said, watching as Oleandra knelt to examine the runes more closely. "Ancient magic is far more instinctive and emotion-driven than modern magical disciplines."
"I don't have years," Oleandra murmured to herself. "I'm not sure if I even have one year..."
She brushed her hand across the silvery pool, tracing the scarlet runes at its periphery with the tips of her slender fingers. Just because ancient magic didn't seem to obey known rules didn't mean it lacked its own. In the world of ten thousand years ago, the Druids had never seemed to struggle using its powers to hunt her down.
"What's this line?" Oleandra asked, pointing to a streak of scarlet script. "The one written right next to the line that switches the Anti-Flight Jinx on or off."
Niamh Fitzgerald leaned in for a closer look.
"I'm not quite certain," she said reluctantly, adjusting her painted bonnet. "Professor Dumbledore added that line himself, shortly before enabling the flight restrictions, four years ago."
Oleandra immediately crossed out the script with a slash of her wand.
In her first and second years, her Tree-Portation Spell used to work perfectly well within the castle grounds. But at the beginning of her third year, Professor Dumbledore and Professor Babbling had finally managed to approximate how her runic spell worked and taken measures to prevent her from teleporting in and out of the castle.
"How stupid was I?" Oleandra sighed, shaking her head. "Trying to Apparate straight into the Great Hall to show off… I actually thought my runic powers were invincible... that I was somehow special…"
Oleandra mechanically reached into her back pocket and pulled out the Marauder's Map, which she had borrowed from Harry and the others— it's not as if they needed it while on the run.
"I solemnly swear that I'm up to no good," she chanted.
She tapped the aged parchment with her wand, and ink blossomed out from the wandtip, spelling out Messrs Moony, Wormtail, Padfoot and Prongs' welcome message. She then unfolded the map and compared it with the castle.
"You may view whichever floor you wish to inspect by calling it out," San Bakar said helpfully. "For example, third floor, please."
The castle of molten silver melted halfway down, revealing a cross-section of the third floor.
"Mischief managed," Oleandra said, tapping the map again, satisfied that it was accurate.
The Map Chamber represented everything she could have ever wished for. If she could interpret and expand upon the restriction Dumbledore had placed on the castle's star runes, she might be able to neutralise Loki's crushing advantage of ten millennia's worth of life lived and runic spells mastered.
Then she would be able to face him on her terms, not his.
A flicker of movement caught Oleandra's eye. Rather than returning to its blank state, a speech balloon had appeared on the Marauder's Map cover, reading:
"Immerse me in the pool."
As a rule, and being rather obstinate, Oleandra made it a point never to obey inanimate objects' orders. "If you don't see where it could house a brain, don't listen to what it says," was common knowledge amongst young witches and wizards… but since the map had been nothing but helpful all these years, she saw no reason not to lend it a hand.