Plan

Meanwhile, in the epicenter of the inferno that is now the village of Bataen, three combatants faced an apocalyptic menace alone.

"No... it can't be... a Chthonic Cerus... not here..." a woman stammered, her voice quaking with fear. Her eyes bulged wide, and she collapsed to her knees.

The knight, who had earlier appeared steadfast and unyielding, now visibly trembled, though he stood his ground.

"Hey! Two of you, keep it together!" shouted a soldier, trying to snap the stunned mage and knight back to reality. But he, too, was petrified. The creature before him defied all comprehension, a nightmare he had only ever seen in movies. He could hardly believe that this abomination was real and breathing.

Ivan, the soldier, spoke again to the two. "You have some sort of magic, right? Why don't you try using it?!"

"T-there's nothing we can do. Cerus are immune to normal magic, and as a C-rank adventurer mage, I can't do anything. It takes nearly a hundred A-rank mages just to defeat a single Cerus," the woman mage explained, her voice trembling. Tears streamed down her face, her hands shaking uncontrollably as she clutched her staff. Every instinct screamed at her to run, but her legs felt rooted to the spot.

Ivan turned his gaze back to Cerus. It resembled a colossal pangolin, but its eyes emitted an eerie purple-blue light. Its claws were razor-sharp, and its spine bristled with crystalline, purple spikes that glowed menacingly in the dark. Each movement of the beast seemed to ripple with raw, destructive power.

"Then... what should we do about this thing..." Ivan stuttered.

"Sire, we know we cannot vanquish this monster, yet I implore thee, with utmost humility and earnest plea, convey these two younglings to safety. We shall do all within our power to buy thee sufficient time to escape," said the knight, his voice laden with the weight of formality and desperation.

"And what of you two?" Ivan inquired, his voice wavering.

"I shall protect my sister at all costs. I assure thee, she will survive, no matter what," the knight responded 

"Negative!," Ivan answered bluntly.

"Civilians' safety is our top priority, so if anyone's staying behind, it's me," Ivan declared, aiming his rifle at the monster's head.

The woman, summoning all her strength, forced herself to stand once more. "I already said this earlier, Mister. We are adventurers," she stated, raising her wooden staff. The azure crystal at its tip glowed brighter. Her voice still trembled, but it was firm with resolve. "And it's also our duty to protect the townspeople."

"Sister..." The knight smashed his large iron shield into the ground and struck his sword against it. "She's right, sire, and in addition to that, our comrades are still here. We are sure they fought with everything they've got.". Both his shield and sword began to glow with a radiant yellow light, casting an ethereal glow in the chaos.

Ivan gave a small nod. He knit his brows, the crosshair of his gun scope locked onto the monster's head, his finger poised on the trigger. He glanced at the twin children, who were still terrified. "Cover your ears for a while," he said, giving them a reassuring smile.

Then he returned his gaze to the monster. "Open fire," he said with calm authority.

The three of them launched their assault simultaneously, each utilizing their ranged attacks. The mage summoned multiple magic circles before her, from which a barrage of crystal projectiles erupted, each impact followed by a small explosion.

The knight swung his sword, unleashing horizontal shockwaves of energy that sliced through the air.

Ivan, meanwhile, unleashed a torrent of bullets from his automatic rifle, the muzzle flash illuminating the night. As the onslaught continued, he decided to lob a fragmentation grenade into the fray.

Explosions and gunfire filled the air. The twin sisters clung to each other, covering their ears against the cacophony.

Finally, the dust began to settle. Ivan ejected the empty magazine from his rifle and replaced it with a fresh one. Leila, the mage, lowered her staff momentarily to catch her breath, while Leonard, the knight, raised his shield defensively.

The three of them observed the aftermath, though they had expected it. Despite their combined efforts, the Cerus monster still stood, unyielding.

"Tsk!" Ivan clicked his tongue. "What a tough bastard, but—"

The Cerus screeched, an ear-piercing sound that forced them all to cover their ears. Through the dust, they saw its eerie glowing eyes and its spine, now brightly illuminated with crystalline spikes.

Leo's eyes widened as he shouted, "EVERYONE! LET'S GET OUT OF HERE!"

Without hesitation, Leo carefully scooped up Reona, the injured child, while Leila grabbed Alisa's hand. Together, they retreated at full speed. Just in time, they escaped as the monster unleashed a devastating beam that obliterated the central well where they had stood moments before.

"What was that?!" Ivan panicked. "For a moment, I saw a light! We were just seconds away from being obliterated!"

As they dashed through the burning streets of Bataen, they could hear loud, fast thuds. "It's running towards us!" Leo shouted.

"We can run all the way to Manilia," Ivan said, glancing over his shoulder. "But it seems that beast is just as fast."

"It will surely catch up with us before we reach the town," the mage said, her voice trembling with fear. "That monster can detect human mana and seeks it out. It will head to Manilia as well."

"Then what should we do..." Ivan pondered urgently.

The knight spoke, his tone laden with formality and respect. "Sire, I shall remain here. I am confident I can delay them and provide you with sufficient time to reach safety."

"No!" Lei's voice rang out, high and angry. "All this time we've been together, and you are the only family I have left. Do you think I will allow you to face them alone and leave me behind? If you stay, then I shall stay as well!"

"But it is our only way, sister. Please, I have vowed to protect you at all costs," 

"Enough, both of you," Ivan interjected, halting the siblings' argument. As they ran, he recalled the damage they had inflicted on the monster. Briefly, he had noticed cracks in the obsidian-like scales of the Cerus, glowing with light and seeping a bright blue liquid. If it bleeds, then it can be killed.

"Do you have something like a cannon or artillery?" Ivan quickly asked, but the siblings' furrowed brows. The mage held her chin and pondered. "Actually…we do have something like that, but still no progress in the capital…"

That came as a surprise for Ivan. But he realised or thought that this might be the era of gunpowder invention. "That cannon, have you already used that against that monster?"

Both the knight and mage looked at each other. The mage replied "Yeah, 10 years ago someone…already used that kind of weapon…" The mage turns her eyes again to her brother, then the knight lets out a slow nod. "It did kill a Cerus." Knight answered. 

Ivan gritted his teeth and smiled. "Then, that's all I need to know."

With that realization, Ivan decided to conduct a quick test. The monstrous army of orcs and the Cerus were still behind them. While running, he grabbed a frag grenade from his vest, pulling the pin with his thumb.

"As long as I hold this grenade, it won't explode. After I throw it, we must all run faster for a moment. You two," he looked at the adventurers, "I want you to observe the damage."

The siblings nodded. Ivan turned and hurled the grenade towards the horde of monsters, counting down in his head. Three, two, one—"Fire in the hole, run!"

BOOM!

The grenade landed directly beneath the pangolin-like monster. "Now look!" Ivan urged. The three combatants glanced back, shocked by the effect. The monster stopped, and parts of its thick armored skin had been blown away.

"Unbelievable..." Leila exclaimed. "What kind of magic is that?!"

"It's a grenade, and it's not magic," Ivan replied.

"Sire, dost thou possess more of these 'grenades'?" Leonard inquired.

"I still have a few, but they won't be enough to kill that beast," Ivan thought. They needed stronger firepower to defeat it. One solution came to his mind.

"I have a plan. Whether we escape to Manilia or not, the monster will reach the town and cause more deaths," Ivan said seriously.

"Then... are you saying we need to defeat Cerus here and now?" Leila asked.

"Forgive me, Sire, I know not the extent of thy strength or the mysteries of thy weaponry, but can we truly vanquish the beast now?" Leonard added, his tone deeply respectful.

"Yes, I have a much more powerful weapon that might kill it. But I need you both to trust me on this," Ivan said,

They finally reached the southern exit of the town.

"What's your plan?" the mage asked.

The siblings waited for Ivan's response. After a few moments, he spoke again.

"I know I said earlier that no one would be left behind, but..." He paused. "Now, I need you both to stay here and buy me enough time to prepare that weapon."

"I'll take the twins with me. I can get them somewhere safer," Ivan continued. "But..." He emphasized. "I want you both to prioritize your safety. Retreat while slowing them down."

"Sire, where is this weapon you speak of?" the knight asked.

"Along this pathway, a few kilometers away. Just slow down their advance. You'll know I'm ready when you see a bright red light in the sky," Ivan explained, referring to flares.

"When you see that, it means the weapon is ready, and you can retreat at full speed towards the light," Ivan explained further.

He handed a grenade to each of the siblings. "To use this, pull the pin and throw it at the enemy. After it lands, count to five, and it will explode."

"Forgive me if it seems I'm making you bait for the monster, but trust me," Ivan looked into their eyes. "Trust me, we can defeat it. Can I count on you to handle this task?"

The brother and sister looked at each other, then nodded slowly. They returned their gaze to Ivan. Leila swallowed hard and said, "Alright, we'll do it, Mister."

To be honest, Ivan hadn't expected the siblings to agree so readily.

The knight then approached and handed Reona, the injured child, to Ivan. "Please, take care of these children," he said, his tone formal and respectful.

Ivan carefully received the child. "Yeah, I'll protect them." Then he gazed once more at the siblings. "Forgive me."

"As long as there's a chance to defeat that monster, we're ready to do whatever it takes," Leila said, her voice resolute.

"Be careful as well, Sire," Leonard added.

Ivan nodded firmly. "The same goes for you. Prioritize your safety. I'll do everything I can to prepare the weapon quickly." With that, Ivan quickly formed a military salute, though the adventurers were unfamiliar with the gesture.