Fire and Sand
Ace's gaze grew increasingly resolute. He understood that now that things had come to this, regret was useless. The only way was to eliminate the Crocodile the Sand before Roy appeared. Only then would he have a sliver of hope of victory.
"Hmph, that look is quite similar to the captain's. It's a pity that your strength is worlds apart from the captain's." Crocodile the Sand thought to himself with some emotion. The strength of these newcomers is truly terrifying.
"Hmph, the outcome of a battle can only be determined after the fight." Ace was also annoyed by Crocodile the Sand's disdain for him.
"To be fair, your strength is indeed quite impressive." The Crocodile the Sand spoke calmly. Although it was just a simple clash, he could roughly gauge the opponent's strength. "If this were two years ago, it might have taken some effort to deal with you. But now, I will show you the cruelty of the sea. Be forever buried in the sand, Quicksand Waterfall!"
What Crocodile the Sand admired most about Roy was his boundless imagination, which gave him a deeper understanding of the Sand-Sand Fruit's potential.
The sea was instantly covered by yellow sand, resembling a desert at sea, barren, withered, and lifeless.
It's important to know that once Logia Devil Fruit User Awakening powers, they can permanently alter the climate and weather of an entire region. If this were to happen in a land kingdom, it would absolutely result in a barren wasteland.
"Could it be that Shichibukai are monsters of this level? If it were me, the flames definitely wouldn't be able to cover such a large area." Ace's pupils contracted sharply. Crocodile the Sand was able to create such a large desert on the sea surface where there was no sand. This kind of terrifying strength was truly chilling.
"We can't just sit here and wait to die, Sun Flare!" A massive amount of flames erupted from Ace's limbs, scattering the sandstorm that was swirling around his body, allowing him to escape from the churning quicksand and fly into the sky above the desert.
"A futile struggle. As long as you remain in this desert, you cannot change your fate of being swallowed up. Sandstorm Burial!"
As the Crocodile the Sand finished speaking, the once calm desert finally erupted into a raging torrent, as if its outstretched fingers were clenched into a fist, ready to crush the fleeing insects into dust.
"Captain, run!" The Spade Pirates, who witnessed everything, were almost scared out of their wits. If they had been hit, they knew what would have happened.
Boom!
The air itself was crushed by the giant hand of the yellow sand, emitting a low groan of unbearable pressure.
"Don't be too happy yet, Mirror Flame!"
The flames coalesced into a pillar, breaking through the sand wall as if they had pierced through the entire desert, and a large amount of flames leaked out from the opening.
"God Fire - Unknown Fire!" Ace gave himself no chance to pause and catch his breath, and the two fiery dragons intertwined and tore at the Crocodile the Sand.
"Desert Greatsword!" The Crocodile the Sand naturally wouldn't choose to "force" him back; the quicksand surrounding him transformed into a greatsword.
A streak of black light spread across the quicksand, piercing through the flames without encountering any resistance.
The flames trembled violently, flickering like a candle in the wind.
"Damn it, it's Armament Haki!" Ace clutched his left shoulder, blood seeping from between his fingers. Clearly, his left hand was practically crippled in this battle.
"Oh? You actually know about Armament Haki. You're quite knowledgeable." Crocodile the Sand raised an eyebrow in surprise. "Since you know the power of Haki, you should understand the difference between us. As Logia Fruit users, your attacks have no effect on me, while I can attack you at will. The outcome between us was already decided from the beginning."
"Anything can happen until the very last moment of a battle. Don't you, as a former Shichibukai, even know that?" Ace mocked.
"Heh, you're really stubborn. But whatever you say, I've always been very patient with the dead."
The orange-red flames shot into the sky again, flying and swirling, gradually transforming from a vortex of flames into a raging storm of fire. The raging flames burned the sky and boiled the sea, and large amounts of seawater were evaporated into white mist that drifted on the surface of the sea, as if one were in a dream.
"You never learn your lesson. Didn't I tell you? No matter how many times this kind of attack comes, it's useless." The yellow sand once again covered the sea, and it continued to spread, blotting out the sun, as if it wanted to swallow the entire sky. Even the raging flames that burned everything seemed insignificant in the face of this sandstorm.
The flames continued to expand, eventually forming a giant sphere of fire, like the blazing sun hanging in the sky, dazzling and blinding.
"If I don't defeat you, I cannot protect the people I cherish, Great Flame Ring - Flame Emperor!"
Ace's boundless potential was fully unleashed at this moment, as if he had returned to his childhood and the moment when he wanted to protect Luffy.
Conqueror's Haki!
All the crew members of the Spade Pirates fainted instantly. Even those on the Golden Ark felt a wave of discomfort, as if an invisible mountain was pressing down on their hearts, making it hard to breathe.
"What! It's Conqueror's Haki!" Roy's Senior Executive were no strangers to Conqueror's Haki, after all, their captain was also a man with such Haki.
"No wonder Crocodile the Sand hasn't come up yet; he must have encountered a powerful enemy!" Anyone who possesses Conqueror's Haki is no ordinary person. If that person appears in the first half of the Grand Line, he is even more worthy of attention.
"Interesting. This is the first time I've met someone with Conqueror's Haki besides the captain." Enel looked at Roy. "Captain, let me go down and take a look."
"On the high seas, there should only be two people who can control such immense fire power. If it were Akainu, Old Sand wouldn't have been able to hold out for so long. So, it must be that man known as Fire Fist." Roy's eyes narrowed, deep in thought.
"Although it's only the most basic Conqueror's Haki, it's already amazing enough. It's terrifying potential." Crocodile the Sand's strength shouldn't have affected him with this level of Conqueror's Haki, but he couldn't shake his habit of underestimating his enemies, so he was momentarily distracted.
In battles at their level, a single moment is enough to accomplish a great deal.
When he came to his senses, the huge fireball was already close at hand, but Crocodile the Sand was not worried at all. If this move had been used before he Awakening, it might have been somewhat useful, but now, Elementalization had become his essence. Even if he was stunned, he would still be in an elemental state that could not be attacked.
"The power I gained from the battle with Vice Admiral Doro, though I'm not yet very proficient, is all I can do but gamble everything on this one strike. Burn everything!" With Ace's inner shout, the orange-red flames were shrouded in black, like a dark sun.
Crocodile the Sand's pupils dilated, and his heart skipped a beat. "Are you kidding me? Are all the new recruits this terrifying these days? It's one thing to have developed Conqueror's Haki Devil Fruit Ability to this extent, but they've even learned Conqueror's Haki and Armament Haki."
Before anyone could think, the dark sun exploded with a deafening roar, and the aftershocks of the released energy stirred up a giant wave a hundred meters high. But this endless wave evaporated in less than a moment, and the dissipating mist spread across the sea, like a fairyland.
(P. S.: In the official novel written by the supreme god Oda for Ace already possessed Armament Haki before entering the New World, so let's leave it at that.)