Frost coated the cracked cobblestones of the lower city.
Kaelen shivered, pulling his thin collar high against his neck. Trading his winter coat for yesterday's single obsidian sphere left him completely exposed to the biting pre-dawn wind. The cold seeped directly into his marrow.
Every step agitated his bruised ribs. The concussive backlash from leveling the Academy training dummy served as a brutal, lingering reminder of his physical limitations. External Anchoring lacked the biological safety valves provided by a functioning internal node. Unleashing raw kinetic force outside the body tore the caster apart just as efficiently as the target. Magic carried a heavy toll, and he paid it in bruised bone and rattled teeth.
Poverty stained the brick walls of this district. Layers of grime and soot pooled in the narrow alleyways.
He stopped outside a reinforced iron storefront. A solitary oil lantern illuminated the display window. The Apothecary Guild.
Behind the thick, warded glass sat rows of amber vials. The lung-rot tincture. His sister required that exact serum every thirty days to keep her respiratory system from collapsing. Failing to secure Lyra Thorne's political patronage meant those shipments stopped permanently. His sister's lungs would crystalize. She would suffocate in her own bed before the winter solstice.
Kaelen tore his gaze away from the glass display. Surviving his upcoming combat deal with Lyra required weapons. He needed ammunition immediately.
Navigating deeper into the labyrinth of the slums, he reached the smuggler's scrap market. Canvas tents flapped wildly in the freezing wind. The harsh stench of burning sulfur hung heavy over the wooden stalls. Scavengers haggled aggressively over stolen copper wire, tarnished gears, and salvaged industrial machinery.
Kaelen stopped at a rotting wooden cart. Broken brass fittings and dull quartz crystals littered the damp planks.
His eyes locked onto a leather pouch spilling cheap glass marbles. Slum children utilized them for street games in the dirt. First Era mages utilized them as highly volatile, disposable kinetic bombs.
An old man with a ruined, scarred cheek stepped out from the shadows of the tent.
"Ten coppers for the bag." The scavenger crossed his arms over his chest.
Kaelen possessed exactly zero coppers.
Drawing his iron-hilted dagger, he placed the weapon flat on the wooden cart. The blade carried dull edges, but the iron remained heavy and solid. It was his last piece of physical protection.
The scavenger traced the faint Academy crest stamped into the iron pommel. "Stolen goods bring the city watchmen."
"The crest is filed down." Kaelen kept his voice entirely flat. "The iron holds raw melt value. Trade the steel for the bag."
Picking up the dagger, the old man weighed the weapon in his calloused hands. He evaluated the profit margin. Tossing the leather pouch across the cart, he claimed the knife.
Catching the bag, Kaelen untied the thick drawstring. He inspected his purchase under the flickering glow of a nearby streetlamp.
These marbles carried severe, dangerous flaws. Tiny air bubbles dotted the interior of the cheap green glass. The spherical shapes lacked perfect symmetry. Standard obsidian conduits featured uniform, predictable density, making the required mathematics clean and safe. These children's toys possessed erratic mass profiles.
Calculating their precise atomic resonance would require agonizing focus. One rounding error would shatter the glass containment mid-cast, blowing his own fingers off before the spell ever reached an enemy. Beggars accepted flawed tools.
Tying the pouch to his belt, Kaelen turned away from the market. Surrendering his dagger left him entirely defenseless in close quarters. He relied completely on his forbidden, volatile magic now.
He ducked into a secluded, lightless alleyway. He needed to run the math before sunrise. Attempting complex density division during a live battle while dodging attacks guaranteed a catastrophic misfire.
Sitting on a crushed wooden crate, Kaelen pulled a piece of white chalk from his trouser pocket.
He selected a single green marble from the pouch. Rolling the glass between his raw, bleeding knuckles, he estimated the overall mass. He factored in the empty volume created by the internal air bubbles. He evaluated a minor surface chip scratching the curve of the glass.
Squatting down in the dirt, he scratched a series of division equations directly into the damp brick wall.
External Anchoring demanded absolute, unforgiving perfection. He cast his awareness outward, isolating the vibration frequency of a low-tier kinetic Thread floating in the alley's atmosphere. He balanced that exact wavelength against the flawed glass density. Carrying the numbers required total mental silence.
Three hundred and eighty hertz.
He ran the division a second time. The quotient verified. The math balanced perfectly. Memorizing the exact frequency, Kaelen erased the chalk equations with the heel of his boot.
Heavy footsteps crunched against the gravel behind him.
Three men blocked the alley exit. They wore rusted chainmail over stained, foul-smelling tunics. Thugs from the local syndicate hunted these specific streets, looking for easy targets before the morning shift started.
"Academy trousers." The lead thug drew a heavy iron hatchet. "Rich boys belong on the other side of the canal."
Kaelen evaluated the distance. Ten yards. His scabbard hung empty at his hip. Retreating backward meant hitting a dead end of solid brick.
"Empty your pockets," the second man demanded, cracking his knuckles.
Rising slowly, Kaelen gripped the calculated green marble tightly in his left hand.
"I have nothing of value."
The leader laughed. He raised the rusted hatchet, closing the distance in three long, aggressive strides.
Kaelen cast his awareness into the damp air.
A kinetic Thread hummed near the alley wall. He grabbed the raw energy. He shoved it violently downward.
Biological instinct urged him to pull the power into his chest. He fought the overwhelming muscle memory, forcing the violent vibration straight into the cheap glass resting in his palm.
Applying his fresh calculations, he clamped down on the frequency. Three hundred and eighty hertz.
The energy fought his mental grip. The microscopic air bubbles inside the glass threatened to destabilize the makeshift containment ward. Blistering heat radiated against his skin.
He held the resonance tight.
The marble vibrated furiously. Searing white cracks spider-webbed across the green surface.
"Are you deaf?" The thug swung the hatchet in a wide, lethal arc aimed at Kaelen's neck.
Kaelen ducked under the rusted blade. He snapped his arm forward, throwing the glass sphere directly at the cobblestones beneath the leader's heavy boots.
He released the containment ward using a microscopic sliver of willpower.
The glass shattered.
Concussive force erupted through the narrow alleyway with the roar of a cannon. The localized shockwave slammed into the three men with the devastating kinetic impact of a runaway carriage.
The sheer output lifted them entirely off their feet. Rusted iron armor crumpled inward, crushing ribs and puncturing lungs. The blast wave shattered the leader's shins instantly. Jagged bone fragments tore through stained fabric and muscle tissue, spraying the alley walls with a heavy coating of arterial blood. The concussive pressure ruptured their eardrums, turning their screams into wet, choking gurgles.
They smashed backward into the brickwork. The three thugs collapsed into the frozen dirt in a broken, bleeding tangle of ruined limbs and twisted metal.
The physical backlash hit Kaelen like a battering ram.
Real-world physics offered no protective buffer. He flew backward, crashing hard through the wooden crates. Rotten planks and rusted nails rained down around him.
Gasping for oxygen, he rolled onto his side in the dirt. His ears emitted a piercing, high-pitched ring. His previously bruised ribs burned with blinding, suffocating agony. The alleyway spun in dizzying, nauseating circles.
He forced his eyes open. Spitting a thick mouthful of blood onto the frost, he pushed himself onto his hands and knees.
Checking his left hand, Kaelen flexed his joints. The fingers remained attached. The skin was blistered, but the math had held perfectly.
The three thugs lay groaning in the rubble, drowning in their own blood. The blast had incapacitated them permanently, leaving behind a visceral, gory display of raw, unshielded magic. He had turned a child's toy into a localized fragmentation explosive.
A mechanical whirring sound cut through the ringing in his ears.
A brass courier bird descended from the smog-filled sky. Hovering just above the carnage, it dropped a small metal cylinder directly into Kaelen's lap. The automaton banked sharply and flew back toward the Academy's elite district.
Kaelen picked up the cold cylinder. Twisting the cap, he extracted a tightly rolled slip of parchment.
Lyra Thorne's elegant, flowing handwriting covered the page.
Tonight. The old transit tunnels beneath the ruined foundry. Bring your weapons.
Kaelen crushed the parchment in his fist. The old transit tunnels belonged to the lowest, most violent dregs of the criminal underground. Sending him there for a combat test was sending him into a calculated death trap.
He touched the leather pouch tied to his belt. He possessed nineteen uncalculated marbles remaining.
He had his ammunition.
Now he just needed to survive the night.