Rumble!
A massive explosion erupted, sending a column of water surging into the sky.
The intelligence operatives had swiftly dispatched the magical beasts and ascended the waterway before they resurfaced onto solid ground.
They had already infiltrated deep inside Jupiter Castle, passing through the sewage treatment facility.
The operatives shed their diving suits and moved in perfect unison, scanning the area for any patrolling guards.
Even without explicit orders, their practiced coordination spoke volumes. Watching them, Dmitri's jaw dropped in disbelief.
'What kind of organization has the Knight of Salvation built?'
Boris detected a mana signal from behind the treatment plant and attempted secure communication via his crystal ball.
He listened to the response emanating from the orb and nodded.
Then, he relayed instructions to the team using message magic.
[Upper command has approved the infiltration. Move to your assigned positions.] At his order, the operatives scattered to their posts.
Boris watched them go before calling out to Dmitri.
"Where is Castro?"
Snapping back to attention, Dmitri replied, "He's probably holed up in his office right now. With the secret weapon and the assault both failing, staying barricaded inside the castle is his best option."
Boris nodded at Dmitri's words.
"Good. Team 1, including Sion and Adol, follow me. Serena and Airen, hold this position and secure our escape route."
Dmitri, observing the scene, asked Boris, "Should I come along?"
Boris shook his head. "Our trust hasn't built up that far yet. We'll consider it after this mission ends."
With that, Boris signaled to Serena.
She, with her metal manipulation ability, immediately understood and formed metal handcuffs around Dmitri's wrists.
Dmitri's eyes widened in momentary shock, but he seemed accustomed to being treated as a prisoner. He shuffled to a corner and sat down.
"I hope you complete the mission successfully. My neck's on the line here. Be careful— Castro and the dark mages stole something from Emperor Nero's legacy in Rom. Who knows what kind of insane weapon might pop out."
Boris nodded at Dmitri's warning and issued a curt order to his team.
"Move out."
*
Bang!
Castro tore at his hair and slammed his fist on the desk in his office.
Shattered bottles littered the floor around him.
"Damn it! Damn it! Damn it!"
In a frenzy, Castro hurled the items from his desk with bloodshot eyes.
He panted heavily before collapsing back into his chair.
"Those cursed allied forces..."
Even unleashing Emperor Nero's secret weapon hadn't inflicted significant damage on the allies.
To make matters worse, both the Red King and the Dracul Knight Order had vanished without a trace.
The mercenaries and legion cohorts he'd sent in a rage had been halted by the sturdy defensive walls. They suffered counterattacks before they could even charge properly, resulting only in mounting casualties.
With a face etched in anxiety, Castro reached for another bottle on his desk.
He uncorked it roughly and downed it in one gulp, wiping his mouth with the back of his hand.
"Hoo, hoo."
As he strained his sluggish mind for a solution, a dark mage resembling a wax doll emerged behind him.
Approaching Castro, the dark mage spoke.
"The mood inside the castle is foul. Dissatisfaction is bubbling up among the mercenaries, and the Breaker Mercenary Company's captain is demanding a meeting with the corps commander."
Rumors were also circulating that Castro had used the dark mages to cast spells on the mercenaries, turning them into berserkers.
If things went south, the mercenaries might spark an internal revolt.
Castro pounded the desk and bellowed.
"Those lowly scum dare! The mercenary captain wants to meet me, the corps commander? Ha! They should just do their damn jobs for the pay. Filthy wretches..."
His eyes dripped with murderous intent as he exuded a feral aura, as if he might storm out and sever the captain's head himself.
But even in his rage, Castro knew that would collapse Jupiter Castle from within.
The dark mage addressed him.
"Corps commander, I have something to say."
Castro, still breathing heavily, slowly lifted his head.
"What is it?"
"There's one way to turn this situation around in an instant." Castro's eyes lit up at the dark mage's words.
He shot to his feet and grabbed the mage, shouting, "A way to turn it around in an instant? What is it?!"
The dark mage met Castro's gaze.
"Among Emperor Nero's legacy transferred to Jupiter Castle, we've discovered a sealed forbidden mystery."
Castro's eyes widened.
"Forbidden mystery? What is it?!"
"I don't know the details. But if the mad emperor sealed it, it must be something lethally dangerous."
Castro furrowed his brow at the dark mage's response.
He sank back into his chair, rubbing his temples in thought.
Then he turned to the dark mage.
"If we don't even know what's inside, how can we control it?"
"If we release it into the allied forces' camp, we won't need to control it ourselves." Castro's eyes widened briefly before he nodded slowly.
Besides, at this point, there were no other options.
Waiting barricaded here for the allies to crumble was risky with the mercenaries seething with discontent.
Ordering his knights to execute the mercenary captain was simple, but it could provoke the enraged mercenaries to burn the castle, fling open the gates, or even defect to the allies.
Rubbing his temples, Castro finally said to the dark mage, "Fine. Whatever this forbidden mystery is, we'll use it to strike the allied forces from behind."
Having decided, Castro descended to Jupiter Castle's underground with the dark mage.
The underground warehouse held various supplies, including items from Emperor Nero's legacy taken from the Rom Imperial Palace.
Many of these, especially those tied to the emperor's obsession with dark magic, were artifacts whose purposes were unknown, stored away for safekeeping.
In the depths of the warehouse, Castro and the dark mage headed to the secluded area housing Nero's legacy.
Other dark mages were already examining the artifacts there.
The wax-like dark mage entered with Castro and gestured to his colleagues.
The dark mages directed hulking monstrosities to carry something before Castro.
Thud!
Before him lay a large black casket.
Its surface bore an unfamiliar emblem that sent an inexplicable chill through him. Castro stared at the black casket. "This is the forbidden mystery left by the emperor?" He reached out slowly toward it.
The dark mage grabbed his wrist with an icy hand.
"No need to approach an unknown mystery." Castro recoiled in sudden alarm.
What lay inside was unclear, but it could be the key to shifting the battlefield. The power it contained had to be immense—he'd nearly been swept away by it.
Calming his pounding heart, Castro asked the dark mage, "How do we get this to the allied forces?"
"Pretend to send an envoy and load the casket onto a cart to infiltrate their camp. Once inside the barriers, awaken the mystery within—it'll sow chaos. Then lead the legion in a full assault."
Castro nodded at the plan.
If it worked, it could shake the allied camp to its core.
'And if it succeeds, I can redirect the mercenaries' ire toward them. That'll quell the internal unrest.'
Castro instructed the dark mage, "I'll prepare the envoy. Time's short—move quickly.
Bring the casket up."
The dark mages ordered the monstrosities to lift the casket again.
Castro ascended the underground stairs with the dark mages.
Partway up, it happened.
Srrrrk—
The solid stairs suddenly turned to sand, sinking to their ankles.
"What the—?"
The dark mages sensed danger and tried to muster their mana.
But their mana flow was disrupted, preventing proper spell formation.
"Urk!"
In the chaos, a sword infused with aura thrust from the shadows, piercing a dark mage's back.
Stab!
The swift killer was none other than the magic swordsman Luther Zemben.
Known in his past life as the Mage Slayer, Luther was Boris's secret weapon.
Wielding an aura-imbued sword in one hand, Luther disrupted the dark mages' spells with precise mana control in the other.
Caught off guard, the dark mages faltered in response.
The wax-skinned dark mage among them suddenly gaped his mouth wide.
Caaaaa!
Black vermin poured from his maw.
Pitter-patter!
The vermin lunged at Luther, but Sion emerged from the shadows and erected a psychokinetic barrier.
Thud-thud-thud!
The vermin halted against Sion's shield. He reshaped it like a blanket, corralling them into a cluster.
Then he constricted the barrier, encasing them in a transparent sphere and crushing them.
The vermin thrashed inside, but they couldn't breach Sion's psychokinesis.
As Sion clenched his fist, the sphere shrank, pulverizing the vermin.
Crunch-crunch!
The crushed remains splattered to the floor.
While Sion contained the vermin, Luther charged forward, severing the rear dark mages' necks in a flash.
Despite his unassuming appearance, he demonstrated terrifying skill.
Slash!
His Seven-Step Demon-Mirror Disruption Sword Art left the dark mages unable to resist, their heads rolling.
Castro, at the rear, gritted his teeth in panic and shouted to the wax-skinned dark mage beside him.
"Hurry! Stop them!"
But Luther's technique had disrupted mana flow, hindering even this apostle-level mage from casting properly.
Desperate, the dark mage drew a dagger and slashed his palm.
Black blood dripped, pooling on the floor.
Moments later, the pool rippled, and something slithered out—like a black serpent or tentacle.
It writhed, climbing the monstrosities carrying the casket.
Then it burrowed into their ear canals, its long body vanishing.
Soon, abnormal reactions gripped the two monstrosities.
Growl—
Their bodies swelled massively, their skin turning deep gray.
Roooar!
Bellowing, they dropped the casket and charged Luther.
Adol turned the floor to sand to trap them, but the monstrosities propelled forward with terrifying speed, leaping up the stairs before sinking.
Roooar!
Fists loaded with propulsion and muscle power aimed to pulverize Luther.
Sion unleashed psychokinesis from behind.
Whiiiine—
He halted their momentum briefly, but they tore free with raw physical force.
Crack—
Luther retreated, but the freed monstrosities couldn't stop their inertia, swinging fists toward the floor.
Boom-boom-boom!
The stairs crumbled under the impact, and the monstrosities tumbled down, unable to withstand their own power.
As they tried to rise, dozens of sandy hands erupted, dragging their limbs into a quicksand pit.
Screeech!
They thrashed to escape, but couldn't break free easily.
With Luther's technique paused, the dark mages could finally cast, but most had already perished in that short span.
Watching from below, Castro ground his teeth. 'Damn it. I need to escape somehow, even if alone...' But then.
"Move and you're dead."
Someone had slipped behind him, a dagger at his throat.
Boris had seized the moment of confusion to capture him.