Here's the full English translation of your passage, preserving the tone, pacing, and character dynamics:
Ding! Congratulations, host. Fusion Card successfully applied to Armament Haki. Your Armament Haki now possesses the property of universal fusion.
The system's ethereal voice echoed once more.
Luo Yu instantly felt a seismic shift in his Armament Haki.
Previously, if he tried to overlay Armament Haki onto techniques like Thousand-Armed Kannon or Hundred-Style Guanyin, the conflicting energies would violently clash and ultimately fail.
But now, with the fusion property granted by the card, Luo Yu could merge them seamlessly with a mere thought—no more worries about incompatibility.
His previously weaker defense could now be bolstered by the fused Armament Haki, taking it to a whole new level.
And if he layered this Armament Haki over his Conqueror's Haki shockwaves…
The destructive power would skyrocket.
"Kid, your Conqueror's Haki isn't all that. Still far from Rocks' level,"
came the aged voice of Feld once again.
But his cloudy old eyes were already filled with shock.
He might've said that aloud, but deep down, he knew: Luo Yu had just single-handedly suppressed two monsters of the old era using only his Haki.
It shattered everything he thought he knew.
If he hadn't barely managed to hold back Luo Yu's advance, he wouldn't have even had the chance to run his mouth.
And if he knew Luo Yu still had a trump card—Beast Mode Haki—he probably wouldn't even be standing.
"Weren't you just full of yourself, brat? Let's see how you plan to suppress me with your Haki!"
Barrett spat blood with disdain.
With Feld backing him up, it wasn't the most honorable way to save face—but Barrett wasn't about to let this go.
"Alright then. I'll get serious."
Luo Yu smiled faintly and took a swig of liquor.
Barrett and Feld froze, eyes widening in disbelief as they saw what Luo Yu was doing.
"That's Armament Haki… You're layering it over your Conqueror's Haki?!"
BOOM!
A violent surge of Conqueror's Haki erupted from Luo Yu once more.
But this time, it was several times stronger—and now coated in pitch-black, liquid-like Armament Haki that crackled like dark lightning.
The two Haki types fused into a monstrous shockwave, crashing down on the stalemate like a tidal cataclysm.
BOOM!
A thunderous explosion rocked the entire level.
The shockwave swept through Level 6 like a hurricane.
Everything in its path shattered like paper.
The cells holding Feld and Barrett offered no resistance.
The two of them, faces frozen in disbelief, were slammed head-on by the fused Haki wave.
CRASH!
All of Impel Down shook violently.
It felt like a giant had rolled over in its sleep.
Even the sea outside roared with towering waves.
Every Marine and guard stationed in the prison was instantly on high alert.
The emergency sirens wailed, echoing to the heavens.
In the 800-year history of Impel Down, this alarm had only sounded once before—when the Golden Lion escaped.
Now, after decades of silence, it rang again.
The entire prison sprang into motion like a massive machine.
Emergency signals were dispatched immediately.
After the Golden Lion incident, Impel Down had become a nervous wreck.
No matter what happened, the first response was always: call for backup.
After all, just half an hour ago, Admiral Luo Yu had delivered two high-value prisoners tied to the Four Emperors.
If two Emperors showed up together…
Even the "impregnable" Impel Down would be in grave danger.
BOOM!
The aftershock of the clash rippled through Level 6.
Dust and debris swirled in the air.
Everyone stared in stunned silence.
The entire level had been flattened.
Many wondered if they were dreaming.
To the outside world, Level 6 of Impel Down was supposed to be unbreakable.
But now, not only had it been breached in an instant—
—it had been done by a Marine Admiral.
Had they not seen it with their own eyes, no one would've believed it.
And those so-called "monstrous criminals," now embedded in the walls, coughing blood and unconscious?
Compared to Luo Yu, who was just trying to clock out, they looked pitiful.
As for Feld and Barrett, who had joined forces moments ago—they were now unconscious, eyes rolled back, plastered into the wall like broken dolls.
If they'd known this would be the outcome…
They never would've dared challenge an Admiral in a hurry to get off work.
No one could've imagined that Luo Yu could weaponize Conqueror's Haki in so many creative ways.
"Ahem… Warden Magellan, sorry about that. I might've overdone it a little and wrecked most of your Level 6. Hope you don't mind,"
Luo Yu said with a sheepish cough, surveying the wreckage.
"Anyway, it's officially past my shift. If there's nothing else, I'd like to clock out now."
Magellan had been preparing a polite reply to the first half of that sentence.
He hadn't expected Luo Yu to be so… direct.
The only silver lining was that all the prisoners were now unconscious—no risk of a riot. A small mercy.
Magellan could only smile wryly.
"Admiral Luo Yu, you're too kind. Thank you for subduing the inmates. We've certainly learned a lot today. I imagine they'll be keeping quiet for quite some time."
"As for Barrett… I doubt he'll be showing off his Haki again anytime soon. We'll handle the rest from here."
"Hahaha! You're right, Magellan," Garp laughed, munching on senbei.
"And that Feld guy—didn't he always say Marine HQ had no real talent? Well, now he's lost more than just face. I'm definitely telling Sengoku all about this when we get back."
"Still, with all that noise just now—even the alarms went off. I'm guessing it wasn't just Impel Down that got spooked. The World Government and Marine HQ probably heard it too. Shouldn't you go explain things?"
Magellan suddenly snapped to attention.
Only now did he realize how serious this had become.
Maybe… he shouldn't have been so quick to take the blame.