Rossum very rarely saw magical mutants. This was because Rossum also very seldom had dungeons appear. It was a rare event that dungeons with monsters would show up, and it was even rarer that a person would become corrupted and transform into a mutant.
Many people in Rossum could go their whole lives not seeing a monster, much less a mutant.
Spirits were not monsters. Spirit Beasts were also not mutants. The term "spirit beasts" referred to a Cultivator who had fully fused with their spirit, gaining the appearance of a beast merged with a human. They looked similar to mutants, but there were some key differences.
Monsters were made of flesh and blood. All monsters were made from living biomass and operated like standard creatures, with organs, bones, muscles, and so on. They were living creatures, and like all creatures, if their bodies were damaged enough, they would die. This was true for even the mighty dragon. Tear out their heart, destroy their brain, slice their head off, or reduce them to minced meat, and that would be enough to kill a monster.
Spirits were not living creatures. In truth, no one knew where they came from or why they were part of this world. They were simply discovered by the race of man when Han Yuan led her forces away from the elves and discovered the nation of Rossum.
Spirits did not operate like living beings, for they lacked bodies. They had no blood, nor did they have bodies in the traditional sense.
When a mage, such as Ash, would use a spell to create a construct out of pure mana, they would actually be creating something very similar to a spirit. A spirit was made entirely out of mana and had no physical form besides the element that made it. They were like constructs, but ones who existed naturally and could think and feel as if they were alive.
In Yujin's case, he was made entirely out of fire mana. He could control his form, allowing himself to become physical, and if he was severely injured, he could heal. Even if his head were blown off, he'd be able to recover. All spirits were like this. That's what made them different from monsters.
Monsters operated like any other creature and had to obey the laws of biology, but spirits did not. They were beings of pure magic and only obeyed the rules of magic. The only way to kill a spirit was to either completely destroy every bit of it so that there would be nothing for it to regenerate from or force it to heal so much that it runs out of mana. Without mana, it'll fade away and cease to be, losing its form entirely.
Naturally, just as monsters and spirits differed, so did mutants and spirit beasts.
A mutant was brought on when a person stayed in a dungeon for too long. They'd be corrupted, and their cells would start to change, as would the Core inside of them. Once the process began, it couldn't be undone, and they'd eventually become a monster, losing their minds and becoming a wild beast of pure instinct. The type of monster they became was dependent on the dungeon that corrupted them.
A spirit beast was made when a cultivator absorbed their spirit into themselves and then tangled their Qi Lines with the Spirit Core's Qi Lines, creating a pure merger. Unlike mutants, this process could be done by untangling the lines and freeing the Core; however, if transformed for too long or done too often, it would become increasingly complex to undo, and eventually the user would find themselves unable to untangle themselves from their spirit.
In this case, they become a true spirit beast or a stage two spirit beast. Like mutants, a spirit beast is a merge of man and monster, or in this case, man and spirit, and this can cause glitches, as the human side is made of flesh and blood, but the spirit side is a being of energy.
When Ken was transformed, she possessed a tail and a pair of ears; however, these things, while attached to her, were made out of solid flame, not fur. The rest of her body was still flesh and blood. This would not be the case if she ascended to stage two. In stage two, her cells would all die, and her physical form would shatter and break, her new Core and Qi lines building a body for her.
When this process is complete, the user becomes a being made of pure mana, like a spirit, but they still retain a humanoid appearance. This stage of power is currently used only by one living cultivator, the mad-wolf Medora, since most cultivators are unable to keep themselves together and explode. Hence, fusing with a spirit and becoming a spirit beast is considered an illegal act due to the risks it carries.
There is still a level beyond this, however.
If a person loses their physical form and truly becomes a being of pure mana, like a spirit or a mutant, they will begin to lose their humanoid form. They'll begin to shift and become more beast-like, and their mind will fade. Eventually, when the process is complete, they'll become a brand-new spirit and lose their mind, becoming a tool for other cultivators to tame and fuse with.
Seeing the power Ken Yuan had, White decided to take a drastic step to win. He didn't care what happened to him. The only thing that concerned him was taking her out. Even if he died, his team would be able to take her corpse, or what was left of it anyway, and be rewarded greatly.
His friends, his wife, and most importantly, his son, wouldn't suffer. He would not allow them to suffer.
And so, with no regard for his own life, White created a Vow. It was straightforward. Fully restore all of his stamina and his mana, and heal his body. Of course, such a Vow would require something of equal value to be given up. White sacrificed his body's natural resistance to the corrupting aura of the dungeon, as well as his Core's ability to fight off a Monster Core.
In other words, in exchange for being fully healed, White allowed the dungeon to instantly turn him into a mutant and then instantly turn him from a mutant into a monster. And since the dungeon was currently in need of a new boss monster, the newly birthed monster was further enhanced and empowered.
In a single instant, White went from dying to rapidly powering up with more mana than he ever thought possible. The force of his power shattered the ground, sending Ken and Olivia flying back.
White yelled in pain, and he felt his body begin to change. As the Vow was made and he gave up his natural resistance, he was immediately transformed into a mutant. A Monster Core formed inside his body. Typically, it would take time for it to corrupt his standard Core, but as part of the Vow, he gave that defense up as well, and so the Monster Core attacked his physical Core.
It was like a cancer, rapidly spreading and swallowing the glowing blue orb that was inside of him. It latched onto it, squeezing and cracking it until it shattered into a million pieces. The Monster Core then devoured and inhaled what was left, and White felt himself change.
In real time, as his Core was being drained, he began to rapidly mutate, transforming into his new monster form.
His flesh began to rip in places along his body as his muscles swelled. His limb returned, and he rapidly healed up all the damage Olivia and Ken dealt him, but then his body was instantly destroyed again as bones jutted out of him, and his legs and arms snapped back. The front of his face began to extend, and he screamed in pain, his mind slowly fading and shattering along with his Core.
From the sides of his head, a pair of horns jutted out, growing and expanding and twisting, and what was left of his flesh shifted into a black color as fur grew across his body. His feet became hooved, and his eyes turned pure red.
When it was all said and done, he was over ten feet tall, covered in thick layers of muscles, and he had the head of a bull.
White had transformed into a minotaur. A mighty bull monster that ruled the labyrinth. Usually, the transformation would end there, but suddenly his body was racked with even more pain as the dungeon began to shake and the roof above split open.
A vast, blinding wave of lights filled the room, and both Ken and Olivia screamed as their eyes burned. Reality itself seemed to shake, and cracks formed along the air. Billions of them twisted together, and they looked like millions or even trillions of galaxies all woven together into a simple shape.
It was a hand. One bigger than anything else, and this hand forged out of reality pressed a single finger into the top of the monster's head. The lights suddenly vanished, and the cracks all sealed up; the dungeon was no longer shaking, but the newly born minotaur let out a loud roar and grabbed at its head.
It was promoted to the boss of the dungeon and was hit with another transformation. It started to swell once more, getting even bigger and reaching nearly fifteen feet. Its muscles inflated, and its fur shone and shifted, becoming a solid brass metal. Cracks formed along its body and filled with fire, and both its hands ignited. Steam poured out of its snout, and the boss finally stood up and held its arms out.
White was now a Brass Bull. A king of the minotaurs and a powerful monster with a sturdy body, these beasts were known for bringing about an end to entire kingdoms.
This was White's trump card. After seeing the power Ken Yuan gained from merging with her spirit and becoming something akin to a mutant, he decided to do the same. He gave himself up entirely, fully confident that the newly born boss could win. He would defeat them both.
Olivia whimpered and winced as she felt her body begin to burn. It was just like when she took the Arcane Knight exam and was in the volcano dungeon. The heat was intense and burning, and the Brass Bull hadn't even thrown an attack out yet. Even Ken looked unwell as she wiped sweat off her brow.
"Seriously?" The woman spat out. "The bastard actually transformed into that? What a sore loser—"
The bull roared. Its jaws opened, and fire gushed out, the dungeon room shaking. The fire around it grew even more intense, and brass liquid started to flow as its limbs melded and reshaped in real time. Then, with sudden speed, the bull threw out a strike as hard as it could at the two girls.
"Shit!" Ken slapped back, and she smacked Olivia away, sending the white-haired girl flying. She then tried to dodge the strike but was a hair too slow. The side of her body was clipped, and she was nearly split in half from the sheer force of it. Ken howled as she felt her spine snap in two, and her upper half was forced all the way back, her head now near her feet.
Her useless body rammed into the wall, and her healing struggled to repair the damage with what little mana she had left. She'd have just enough to heal this damage, but then after that, she'd lose the ability to stay connected with Yujin and would have to let him rest.
Not that it mattered, though, because as she was still recovering, the bull suddenly appeared over her and went to crush her to death. Her spine hadn't fully recovered, and she didn't have enough mana to form a shield. Ken stared in horror as the hand came toward her, but at the last moment, something rammed into the side of the bull's head.
"Row Blood Bolt!" The spell didn't even harm the creature but did make it pause, and it shifted its gaze toward the witch who had dared to strike it. Olivia gulped but stood her ground, pointing her wand forward. "That's right! Look at me, ugly!" She tried to sound confident despite the fact that she only had enough blood left for one more spell, and worse yet, her polymorphed form would come undone, leaving her back in her default state, which had already used all three of her spells and all her mana up.
Fighting this thing and winning weren't outcomes she could see. Instead, Olivia decided she would distract the creature and give Ken enough time to recover. Once that happened, the two of them could run for their lives and attempt to escape the boss.
This was easier said than done, and her eardrums nearly exploded as the bull roared at her and came stomping forward. It was shockingly fast, and she didn't even have time to attempt to dodge or put up a barrier as its hand came sliding down toward her.
"Row Shadow Vault."
The bull's foot jerked down as the shadow beneath it suddenly opened, and it began to sink. This caused its swipe to go wide, and its hand rammed into the wall behind Olivia, shattering it.
"Davi!" Olivia felt a sudden sense of relief as she heard her friend's voice, and she turned in his direction. With him here, they might actually stand a chance. "Thank Haru, can you-" Olivia's smile faded when she saw Davi.
Davi looked like he was struggling to stay on his feet. His armor was barely held together, with cracks and dents covering it. He was missing his helmet, also showing off a bruised and beaten face. He looked like he had been through the wringer, and clearly, whatever fight he had gotten in hadn't been an easy one. His usually vibrant aura was also way smaller than it normally was, a faint blue glow barely flickering around him.
"I was kind of hoping you'd be at full power…" Olivia said flatly.
"Don't worry." Davi lifted Storymaker and pointed the blade at the bull. "I got this." He ran forward and coated his blade in mana and then swung it out as hard as he could. His blade bounced off the metal of the bull, not even hurting it in the slightest. "Shit. I don't have this."
The bull tore its way out of its vault, ripping its leg free, and fire blasted out of it, nearly burning Davi alive, but he narrowly jumped back.
"What now?" Olivia yelled.
"We run." Davi appeared next to her, casually picked her up with one arm, then dodged out of the way of another swipe as the beast tried to squish him. He ran forward, grabbed Ken, and then began to run heroically away from the bull, which started to give chase. He had Olivia over his shoulder, and she was facing the bull, watching in horror while it got closer and closer. He carried Ken under his shoulder, keeping an arm hooked around her waist and dangling her, not able to be gentle as he ran with everything he had.
"Is this seriously the best plan you could come up with?" Ken demanded, glaring up at him.
"You got a better idea?" Davi shot back.
Ken opened her mouth, about to retort, but then she glanced back at the Brass Bull. "Run faster!" Her spine finally finished healing, and she felt the last of Yujin's energy vanish. Her spirit was forcefully disconnected from her, and he was ripped out of her body, turning into a ball of glowing light. Her hair and eyes reverted to their standard colors, and her power dropped considerably.
"Forgive me, Lord Ken Yuan." Yujin's voice came out weak and was practically a whimper. "I must regain my strength."
"It's fine! Recover fast!" Ken held her gourd out to him, and he was sucked back inside.
"Guys!" Olivia said in a panic. "It's getting closer!"
The Brass Bull smashed through walls and barriers, plowing through everything that got in its way, and it was rapidly catching up to the two of them. It took a sudden leap and used fire the same way Ken did, launching its massive body forward like a rocket. It appeared over Davi and the two girls, and it came crashing down, ready to squish all three of them!
"Row Shadow Vault."
Olivia and Ken felt themselves suddenly go from being burnt alive to unbelievably cold as Davi opened his vault and dragged the three of them inside of it. They dropped into the black void, and he closed the vault right as the bull landed.
Ken's teeth clenched, and she felt ice begin to spread across her skin. Olivia was the same, rapidly freezing as well. With Yujin low on mana, Ken couldn't simply use a fire spell, and so she had no way to fight off the intense cold.
The chill was just like the blizzard that had appeared when she first saw that dragon. It was intense, and she knew if she stayed here for too long, she'd die. This wasn't a place that could support life.
Davi rapidly shifted his vault and brought in two warm blankets, which wrapped around both the women, ensuring they wouldn't instantly die. Even with that, they wouldn't be able to stay in here for very long.
"W-Where is this place?" Ken asked, looking around in shock.
"My vault." Davi floated his arms and crossed his legs as he floated in the void. He didn't seem bothered by the cold and also wasn't weirded out by the flying, unlike Olivia and Ken, who were both struggling not to spin out of control. There was no gravity here, and the slightest bit of motion caused their entire body to turn in that direction. "I took us here to escape that last attack. If I had any potions left, I'd bring them here, but sadly, I don't. Instead, we'll just have to catch our breath and get ready for round two quickly."
"Fuck that! Just teleport us out of here!" Ken ordered.
"My vault doesn't work like that. I can only take us back to the spot where that monster was."
"Seriously? Damn." Ken frowned. "Okay, then let's wait here. I think I can survive for at least an hour, maybe longer if we take drastic measures to get warm. Surely the monster will leave after that amount of time, and we can just pop out and run for the exit while its focus is elsewhere."
Again, Davi shook his head. "Sieg is still in the dungeon, and he might run into that thing. I don't want that happening. Not to mention, there are other things we have to worry about that make staying in here for a long time not possible." As if on cue, the sound of a bird screeching came from the darkness, and both Ken and Olivia felt a new wave of terror hit them.
What the hell was in this vault? Olivia bit her lip. "Can you try pulling the monster into the vault?" She asked. "We could trap it or something?"
"Sadly, that won't be possible." Davi sighed. "Maybe if I were at full power, I could, but I don't have the mana to pull off a Vil-level spell at the moment, and my Row Shadow Vault isn't big enough to drag something like that in. It's strong enough to break out if it tries. To be honest, I doubt even Vil would be enough, and I have no idea how to do Ril-level spells, so that's out of the question."
"So, then what the fuck do we do?" Ken growled. "All three of us are running low on mana, so fighting that thing isn't possible. We also can't stay here long enough to recover."
"I have a plan." Davi tilted his head and hummed. "I'll hold the thing off while you two run away—"
"No." Both girls said flatly.
"We're not doing a 'some sacrifices themselves for the rest of the team' ploy," Olivia stated.
"Liv here is right." Ken agreed. "I don't particularly like either of you two, but I guess I don't dislike either of you two either. We all make it out, or none of us make it out. That's just how it'll be."
"When did you two get so chummy…"
Ken shrugged. "Well, I guess if it has come to it, I do know one way we could regain our energy." She rubbed her chin in thought.
"You have a potion or something?" Olivia asked.
"Or something." Ken looked a little nervous, and she coughed into her fist. "We can do Joint Cultivation."
"I don't know what that is." Olivia frowned.
"You seriously don't know what it is?" Ken's cheeks turned a little red, but she kept her cool and let out another awkward cough. "I don't think it would work for you, but Davi and I could do Joint Cultivation and attempt to regain our Qi. This isn't the best place, and it's awkward, but…"
"I still don't know what Joint Cultivation is." Davi gave Ken an odd look.
"Basically, you trade Yin and Yang energy." Ken tapped her fingers together. "The passing of energy causes a growth-like effect and a swelling of power, which can rapidly restore Qi and even grow the Core, allowing someone to become stronger. Men have Yang energy, and women have Yin energy, so they can perform Joint Cultivation and cause this swapping-like effect to happen if a man and a woman do it. Two women or two men can't perform it, but I guess it would be possible for two men and a woman or two women and a man to do it all together, but it would be a bit more complicated…"
"That sounds awesome!" Olivia said excitedly. "So, it's like a technique that requires another person to do? And it could let you and Davi get all your mana back?"
"What's the catch?" Davi asked skeptically.
Ken let out a weak chuckle. "Well, the process of trading energy is a very delicate thing. There are various methods and ways to do it, but the only one I know involves… sex."
Olivia felt her face heat up, and she tried to process what she was hearing. "S-Sex? Whoa, whoa, whoa, you mean like… Sex, sex?"
"Is there another kind?"
"L-Like really? Why does it work like that?!"
Ken also looked embarrassed. "I'm not the one who made it! Joint Cultivation is a practice my clan uses. The exchange of energy does work, and I don't have any other idea on how we could take that bull out besides that. I don't like it either, but it's that or die."
"As fun as that sounds, I'll have to pass," Davi said dryly. "You already said you don't know if bringing Olivia in would work or not, and she doesn't have long left in her Polymorph form. I don't think she'll be able to survive in here once it wears off. Plus, we really can't stay here for that long, and you'd likely freeze to death mid-act."
"So, if we weren't in the vault and didn't have a time limit, you'd do it?" Olivia raised an eyebrow.
"Yes, one hundred percent. It doesn't even need to be for regaining strength; I'd tap that any day." Davi's face and tone remained blank as he gave a thumbs-up.
Ken looked like she wanted to retort but eventually shrugged. "I'll take it as a compliment." She gave Davi a thumbs-up right back at him.
"When did you two get so chummy…" Olivia gave them both a suspicious look. "Either way, we need to figure some plan out."
"That monster's scale is tough." Davi lifted his sword and glanced at Storymaker. "I can't cut through it, but I might have a way to puncture a hole in it. I don't think it could kill it, though."
Olivia's eyes lit up. "Actually, if you're right, I think I know how we can beat that thing."
"Oh yeah?" Ken smirked. "Look at you. I knew you were smart. What's the plan, Liv?"
Olivia clutched her wand as tightly as she could, then explained what they needed to do to truly defeat White.