One Piece: Transmigrated as Crocodile

Ace had also challenged his father before. While this wouldn't be a reason for him to stir up trouble with Crocodile, it wasn't likely that he would acknowledge him either. For now, Crocodile was just a stranger he happened to encounter. But as a pirate, Ace was still quite interested in strong opponents, especially those who, like him, wielded the power of a Devil Fruit. However, since he was currently on the hunt for Blackbeard, he had no plans of battling Crocodile anytime soon.

If Rosen remembered correctly, at this point in time, Ace was not only more destructive in terms of his abilities than Rosen, but he should also have learned Haki. This was noted in the official novel about Ace's life, where he mastered Haki during a tough battle with Rear Admiral Doro. Rosen couldn't recall the exact timeline of when Ace had mastered Haki, but he knew that this period marked the final journey of Ace's life. So, it was certain that Ace knew at least the basics of Haki, and he had displayed the potential for Conqueror's Haki since his youth.

Therefore, from every angle, Ace was stronger than Crocodile at this point. Before joining Whitebeard, he had even turned down an invitation to become one of the Seven Warlords of the Sea, and his official bounty had already reached 550 million Berries. 

However, in this desert, Rosen was confident that he could use his abilities to handle Ace, whether he needed to escape or engage in battle. With the terrain on his side and the often unpredictable nature of battle, he wouldn't say he had no chance. Still, judging by Ace's demeanor, he didn't seem intent on fighting.

Rosen, on the other hand, was eager to test his strength. The little pirate he had faced earlier had barely posed a challenge. Even if he couldn't win against Ace now, at least he would be able to escape in the desert, where no one could stop him. Besides, Rosen felt confident that if they were to spar, Ace wouldn't go all out to the point of trying to kill him. Rosen believed Ace was not so cruel, at least based on what he knew of him.

He would eventually face people at Ace's level. Why not experience it now? After all, Rosen figured that if he survived the journey, it was very likely he would cross paths with a Yonko worth Four to five billion Berries in bounty.

"Portgas D. Ace, how about a spar?" Rosen proposed.

"It seems you're eager to fight," Ace said, adjusting his hat, unbothered. 

In truth, Ace was curious to test Crocodile's strength as well. After all, fighting strong opponents made one stronger. Initially, he had thought it unnecessary to waste time on such a battle, but if Crocodile was offering, things were different now. There was no reason for him to back down, whether for himself or for the name of Whitebeard that he carried.

"Sandstorm!" Rosen didn't waste any words. Knowing Ace's strength, he didn't hold back. A whirlwind of sand formed in his right palm, gathering more of his Sand-Sand Fruit power. The sandstorm grew violent as it spiraled toward Ace.

"Fire Fist!" Ace's expression turned serious as he saw the sandstorm. He couldn't afford to be careless against a Warlord of the Sea. His right hand ignited into a raging flame, warping the already dry air around him, which began to shimmer in waves from the heat.

With a mighty explosion of air, Ace hurled a massive fireball at the sandstorm. The heat and gusts of wind it created made Rosen uncomfortable. 

Boom! The collision between sand and flame erupted, with both elements blasting apart in a violent explosion. The fiery shards and sand scattered in all directions with incredible force. Fortunately, they were in an uninhabited area, or this single attack could have destroyed countless buildings and injured innocent bystanders.

This was why most users of Logia-type Devil Fruits were seen as natural disasters.

"Desert Sunflower." Rosen pressed his hand to the ground, and suddenly, the sand beneath Ace's feet caved in, creating a deep pit. But Ace's reaction was faster. Just before the pit formed, he sensed the danger, and his feet erupted with flames, propelling him into the air with the help of the flames, keeping him temporarily suspended.

"Arc Crescent Dune." Taking advantage of the moment, Rosen swung a curved sand blade at Ace. Though it lacked much offensive power, if it hit, it would drain most of a person's moisture, enough to render most opponents incapable of fighting.

"Flame Pillar." But Ace, a battle-hardened fighter, immediately reacted. He spun in mid-air, and a towering pillar of fire shot down toward the ground, instantly filling the sand pit and spilling out, creating a wave of fire that surged toward Rosen.

"Desert Wall." Rosen quickly retreated, raising his right hand. A thick wall of sand surged up in front of him, blocking the advancing waves of fire. The fire crashed into the sand barrier, bursting into a violent explosion. 

The sand wall shattered, and scattered embers landed on Rosen, but he quickly summoned sand to smother the flames. 

"Fire Gun!" As Ace landed, flames poured into the sand pit, filling it with fire. Using the flames as footing, Ace darted across the ground, his fingers shooting fire bullets in rapid succession. 

Whiz! Whiz! Whiz! Each bullet zoomed toward Rosen, burning with intense heat. 

"Elemental." Rosen transformed into his element, letting the flames pass harmlessly through him. While Haki could restrain Logia types, if he used his elemental form effectively, he wouldn't be hit.

Rosen briefly wondered if Ace could imbue his fire with Haki, but it was safer to be cautious. 

He then realized something that might give him an edge: Could his sand counter Ace's flames? If not, without understanding Haki, how could he expect to win in this battle? 

Normally, fire couldn't ignite sand, and sand could extinguish flames to some extent. So, on paper, Rosen's power had a slight advantage. But if their overall strength and endurance didn't match up, this advantage wouldn't matter much. It was like Aokiji's Ice-Ice Fruit—if developed properly, it could freeze magma. So the balance between the elements wasn't always absolute. 

For now, it seemed Rosen's Sand-Sand Fruit had the upper hand. He hadn't expected this.

"Multiple Sandstorms, Surround and Attack!" Rosen summoned nearby sand, creating four powerful sandstorms around Ace.

Ace smiled faintly, suddenly transforming into a whirlwind of flames. His hands slammed onto the ground. "Super Large Flame Pillar!"

Boom! The fire pillar erupted, blasting into the sandstorms, causing massive explosions with each impact.

In that instant…

"Desert Greatsword." Rosen quickly judged the situation. The sand beneath Ace's feet shifted, forming a massive, horizontal sword. It swung toward Ace.

"Armament." Ace gritted his teeth. The sword, sharp enough to slice through rocks, collided with him, but instead of slicing through, sparks flew off his body. 

Haki?

Rosen was taken aback.

"Mirror Flame." Ace suddenly shot a massive burst of fire from his arm, hurling it at Rosen. The flames were overwhelming, burning everything in their path.

Rosen, caught off guard, immediately summoned sand to form multiple barriers. But the sand walls were quickly obliterated.

Boom! Rosen took the full brunt of the attack. Fortunately, the blast had already been weakened by the distance, and though Rosen had already switched to his elemental form, he could feel the heat singeing his body.

Though sand could extinguish flames, fire could still scorch sand. Even though the damage wasn't severe, it was a reminder that the battle's effects weren't nullified by elemental interactions. And that was with both of them lacking Haki.

Ace suddenly surged forward, closing the distance between them. In an instant, he was right in front of Rosen. But Rosen could sense the gap in their physical capabilities. He realized that continuing the fight would turn into one-sided defense for him. 

More importantly, he noticed that his attribute stats had changed.

Rosen immediately withdrew all his sand defenses and calmly spoke, "I surrender."

Ace's attack stopped abruptly.

(End of Chapter)