What if Boros survived(OPM)

Orochi's body morphed into a grotesque, monstrous form as numerous dragon heads sprouted and launched themselves at Boros.

The alien smirked and lunged straight at them. "Let the battle begin!" he exclaimed, punching the dragon heads one by one, making them explode in bursts of fiery energy.

Orochi retaliated swiftly, sending dozens of dragon heads from all directions toward Boros while he was mid-air. Boros, however, used the heads themselves as footholds, darting and springing around the cave with ease.

As Boros maneuvered through the onslaught, he attempted to land another punch, but his fist was suddenly redirected at the last moment. Confused, he adjusted his stance for a second strike, but the same thing happened again.

Unbeknownst to Boros, Orochi had mastered the Water Stream Rock Smashing Fist, a signature technique of Silverfang, the greatest martial artist on the planet. Orochi had learned it through a monster he recruited—a former student of Bang, the third-ranked hero.

Taking advantage of Boros' hesitation, one of the dragon heads slammed its jaws into him, sending the alien crashing into the rocky wall of the massive cavern.The dragon's mouth began to glow, and a red energy beam shot out at point-blank range. Boros, unfazed, grabbed the dragon head by its lower and upper jaws and tore them apart with his bare hands. He leapt away just in time to avoid several more beams fired by Orochi.

Running along the cavern wall at incredible speed, Boros dodged piercing horns and a hailstorm of energy blasts from dozens of dragon heads. Despite his agility, the repetitive attacks were beginning to bore him.

"This is getting tedious," Boros muttered as he sprinted across the cave for the fifth time. Deciding on a new tactic, he propelled himself off the wall and toward Orochi's legs, aiming for a direct strike.

Before Boros could connect, Orochi jumped into the air, his dragon-headed tentacles anchoring themselves to the cavern walls and suspending him high above the molten lake below.

"Take this!" Orochi roared as dozens of dragon heads aimed downward, unleashing beams and flames that engulfed the entire bottom of the cavern in a fiery inferno.

Boros stood firm amidst the flames, tanking the assault. Hidden by the glowing beams, he sprang upward and grabbed one of Orochi's dragon heads. Using it as leverage, he launched himself straight at Orochi's face.

Orochi dodged to the side, forming a massive fist with his tentacles and striking Boros mid-air. The blow sent Boros flying into the cavern ceiling, followed by a barrage of energy beams that pushed him upward.

............…..

Above the Battleground

The monsters above could hear and feel the tremors, even from far away. The ground shook violently as if the entire base might collapse.

Gyoro Gyoro frowned. "What is Orochi doing? He should have finished this already."

The air grew warmer, and Gyoro assumed it was the heat from Orochi's energy beams and fire attacks. For a moment, she considered evacuating the monsters but dismissed the idea.

"Orochi is my loyal, brainwashed guard dog," she thought. "He wouldn't do anything to jeopardize my plans."

Little did she know, Orochi, having found his perfect sacrifice, no longer cared about anything but his own reincarnation.

............…

The Battle Resumes

"This is fun," Boros muttered, smirking with excitement. The beams didn't harm him, but figuring out how to land a hit on Orochi was proving to be a thrilling puzzle.

Planting his feet firmly against the rock ceiling, Boros pushed back against the beams and propelled himself back into the cave.

Orochi ceased his attack just before the beams could breach the Monster Association's main chamber.

"I am impressed by your performance," Orochi said. "But can you keep up when I condense my power?"

Orochi's body began morphing again, his tentacles and dragon heads merging and twisting together to form new, muscular limbs. His shape condensed into a more humanoid form, with even more flames radiating from his body.

Boros observed with a grin, noting the similarities between Orochi's new form and his own released state.

"I see," Boros said. "You've been holding back this entire time. Good thing I didn't go all out from the start; otherwise, I would have killed you before seeing this."

Boros powered up, the cracks in his body glowing an intense blue. A massive aura of pure energy erupted from him, illuminating the cavern in a blinding light.

Both combatants now revealed more of their true strength, and the battle resumed.

............…

Above Ground

Saitama and Genos felt the tremors from above. Initially dismissing it as an earthquake, they grew suspicious as the rumbling continued in a rhythmic pattern.

"We should check it out," Genos suggested. "There might be something happening underground."

Saitama shrugged. "Sure, why not."

............

Underground

Boros darted around the cavern like a flash of light, while Orochi used his numerous appendages and area-of-effect blasts to keep him at bay.

Although Boros was faster, stronger, and more durable, Orochi's precision and mastery of martial techniques made him a challenging opponent. Using the Water Stream Rock Smashing Fist, Orochi deflected Boros' strikes and countered with devastating blows.

Boros charged relentlessly, but Orochi either dodged or redirected him every time. Despite his overwhelming power, Boros was unable to land a meaningful hit.

Growing frustrated, Boros let out a thunderous roar. "HAAAAA!" His aura spiked, and blue lightning crackled around his body as he unleashed the full power of his released state.

Orochi took notice. "He's even stronger now," the Monster King realized. "His raw stats are enough to surpass my abilities. I must act quickly."

Orochi grew a massive tail and drove it deep into the earth's crust.

"I will use my full power as well," Orochi declared. "I shall draw energy directly from the planet's core."

The ground trembled violently as Orochi absorbed a colossal amount of energy from the Earth. Volcanoes erupted, cities crumbled, and mountains shook as the planet itself seemed to react to Orochi's actions.

A massive mouth opened on Orochi's chest, glowing with fiery energy.

"Bathe in this," he roared. "Gaia Cannon!"

A blinding beam of energy, dozens of times more intense than anything before, shot out from Orochi's chest. The cavern walls began to collapse under the immense pressure and heat.

Boros crouched low, gathering all his energy. "Let's end this." He leapt straight into the beam, punching through it with sheer force.

"RAAAHHH!" Boros' fist collided with Orochi's chest, piercing through the Monster King and leaving a massive hole in his body.

Orochi fell into the molten lake below, his eyes flickering as he stared up at Boros.

"You... bastard..." Orochi muttered weakly. "What have you done..."

Boros landed on a rocky ledge, peering down at the fallen king.

"I went all out in my released state," Boros said calmly. "Defeating you was a challenge, but in the end, you were a puzzle, not a worthy foe."

"Your ultimate move drew a tiny fraction of the planet's power. Mine, on the other hand, could destroy this Earth entirely."

As Orochi desperately reached for his crumbling altar, Boros observed the mural revealed behind it.

"Seems you misunderstood your fate, Orochi," Boros said. "You were the sacrifice, not the God."

The cave collapsed entirely, burying the altar as Boros walked away, the sole witness to the mural's hidden truth.