The sudden, ringing silence was almost as jarring as the fight itself. The only sounds were the echo of their own ragged breaths and the gentle lapping of the neutralized sludge against the concrete walkway. The air, thick with the smell of burnt hairspray and ozone, was slowly clearing.
Kai leaned heavily on his saber, every muscle in his body screaming in protest. His shield was a ruined mess, the metal warped and blackened, a large section eaten away by the creature's acid. It was useless now. He unstrapped the mangled buckler and let it fall with a heavy clatter into the murky water.
"Is everyone okay?" he asked, his voice hoarse.
Ben was leaning against the tunnel wall, his face pale in the flashlight's beam, his glasses askew. "Physically, I believe so. Mentally... I may need to re-evaluate several core tenets of biology."
Elara rushed over to Kai, her eyes wide with terror and relief. "Kai, your arm! The shield-"
"I'm fine," he assured her, showing her his unblemished forearm. "It didn't get through. But the shield is gone."
Her eyes fell on the milky-white orb that floated serenely above the water where the Sludge's core had been. It pulsed with a soft, internal light, a beacon of calm in the filthy tunnel. "What... what is that?"
Kai approached it cautiously. Unlike the Scuttler cores, this object didn't feel inherently aggressive or chaotic. It felt... calm. Natural. He focused his Observe skill on it.
A blue box appeared, its text a welcome sight.
[Heart of the Tunneler]
[A unique biological core formed within a creature native to the subterranean depths. Contains purified energy and adaptive properties.]
[Options:]
[1. Absorb: Gain a large amount of raw XP.]
[2. Integrate: Permanently bind the core's properties to your System. XP gain will be minimal, but a new, unique skill will be generated.]
Kai stared at the options. XP was tempting. He was still a long way from Level 6. But a unique skill... that was invaluable. His swordsmanship skill had saved his life multiple times. Another ability, especially one from a creature this resilient, could be a game-changer. The choice was easy.
He focused his intent on the second option. "Integrate," he whispered.
He reached out and touched the orb. It didn't dissolve into light like the monster cores. Instead, it felt cool and smooth, like polished marble. As his fingers made contact, it seemed to liquefy, flowing up his arm in a stream of cool, white light. It wasn't painful; it was a strange, tingling sensation that spread through his entire body. He felt a subtle, fundamental change in his own biology, as if his skin was becoming tougher, more resilient on a cellular level.
[Integration complete.]
[XP Gained: 25]
[XP: 395/600]
[New Skill Generated: Acid Resistance (F-Rank)]
[Acid Resistance (F-Rank): Your body has adapted to corrosive agents. You now possess a minor resistance to acidic damage.]
It was an entirely new type of skill. Not an active ability, but a passive one. A permanent upgrade to his own body. He looked at his hands, which appeared no different, but felt... stronger.
"Kai? What just happened?" Elara asked, her voice laced with concern. "What did you do?"
"I got a new skill," he said, the words sounding absurd even to him. "Resistance to acid."
Ben pushed his glasses up his nose, his academic curiosity overriding his fear. "Fascinating. The System isn't just granting you abilities, it's allowing you to assimilate the biological traits of slain organisms. This is a form of horizontal gene transfer on a metaphysical level! Kai, your potential for adaptation is theoretically limitless!"
"Great," Kai said dryly, flexing his fingers. "Right now, I'd settle for a new shield."
The fight had cost them. Their only light source, the heavy flashlight, was flickering, its battery weakened. Elara's makeshift flamethrower was a one-shot weapon. And Kai was now without his primary piece of defensive gear.
They took a few precious minutes to rest. Elara passed around a water bottle and they each ate a protein bar in silence, the grim reality of their situation settling back in. They had won, but the victory felt temporary. The tunnels were long, and they had no idea what other native horrors awaited them in the dark.
"We have to keep moving," Kai said finally, getting to his feet. He picked up the half-empty can of hairspray, weighing it in his hand. It wasn't much, but it was better than nothing.
Ben nodded, tapping the flashlight nervously. "The battery is running low. We need to reach the exit grate before it dies completely."
With a shared look of grim determination, they pushed onward, their steps echoing in the vast, oppressive darkness. The path ahead was clear, but the memory of the Sludge, and the knowledge that they were invading a place with its own monstrous ecosystem, hung heavy in the air