Borin argued vehemently with the elders, leveraging Isolde’s unsettling experience near the lift shaft and the mounting evidence of disappearances. Finally, grudging permission was granted: investigate the upper sections of the lower mines, find proof of the disturbances, determine the fate of the missing patrols, but go no deeper without explicit council approval. They were assigned two grim-faced Duergar guards as escorts, their presence feeling as much like surveillance as support.

  The transition was stark. Heavy, rune-etched gates groaned open, revealing tunnels far older and rougher than the relatively maintained upper levels. The air grew heavy, thick with the dust of ages, the damp scent of deep earth, and the faint, acrid tang of geothermal activity mingled with Blight. Darkness pressed in, barely held at bay by Borin’s lantern and the guards’ dimmer ones. Silence reigned, broken only by the drip of unseen water and the crunch of their boots on the uneven stone floor.

  Strange, phosphorescent fungi clung to the walls in patches, casting an eerie, pale light and sometimes pulsing faintly, different from the lichen above. Corrupted mineral veins snaked through the rock, glowing with a sickly violet or green tinge.

  "Stick close," Borin grunted, his voice low, automatically falling into the cautious cadence of an experienced miner. "These levels... haven't been worked proper in generations. Unstable ceilings, gas pockets, old traps the first kin set." He pointed his pick towards a section of wall. "See those markings? Old clan boundary ward. Weak now, likely corrupted."

  Edmund moved at point, sword drawn but held low, his shield ready. His eyes scanned constantly, peering into the oppressive darkness ahead, noting the way shadows seemed to writhe at the edge of the lantern light. Lyraen moved silently behind him, their pale eyes absorbing every detail – the unique fungal growths, the subtle shifts in air pressure, the way the stone itself seemed to groan under some unseen pressure. Isolde walked near the center of their small group, flanked by the impassive guards. The 'presence' she'd felt near the lift shaft was a constant thrum here, a background radiation of cold, alien awareness that made her skin crawl and the taint beneath her glove ache persistently. She focused on keeping her senses open, analysing the energy shifts, trying to ignore the growing dread.

  They found the first signs of trouble less than an hour in. A heavy ore cart lay overturned, its contents spilled across the tunnel floor, timbers splintered not by accident, but by deliberate, focused force applied to structural weak points. Nearby, scorch marks marred the walls – not from fire, but from some kind of corrosive substance.

  Further on, they found the remnants of a barricade, hastily erected and just as violently torn down. Broken spear hafts lay scattered alongside scraps of Duergar mail and dried patches of dark ichor. No bodies.

  "Missing patrol," one of the Duergar guards muttered, his face grim, touching a protective rune etched onto his breastplate.

  As they advanced, the evidence of malicious intent grew clearer. Support beams showed signs of being deliberately gnawed through by Blighted acid or fungus. Warning runes near unstable sections had been defaced or actively countered by crudely scratched spiral-eye symbols that seemed to absorb the runic light.

  "It's learnin' Duergar work," Borin growled, examining a sabotaged pressure-release valve near a geothermal vent. "This wasn't just smashed; the locking mechanism was deliberately jammed. Only someone who knew how it worked... or somethin' that watched someone who knew..."

  They rounded a corner into a wider section, an old staging area. And the Blight was waiting. Not a mindless swarm, but an ambush. Two hulking, Blighted Duergar, their flesh grey and split, eyes glowing with malevolent emptiness, lumbered from behind stacked mine carts, wielding heavy mining hammers like weapons. Simultaneously, smaller, skittering creatures composed of bone shards and blighted fungus dropped from crevices in the ceiling, flanking them.

  "Ambush!" Edmund yelled, engaging the nearest Blighted Duergar. The creature swung its hammer with surprising speed, mimicking mining techniques twisted into deadly attacks.

  The guards moved to intercept the skitterers, their axes ringing against blighted bone. Borin roared a Duergar battle cry, his pick finding purchase in the corrupted flesh of the second Blighted miner. Lyraen moved with calm precision, identifying weaknesses. "Target the fungal clusters!" their clear voice cut through the din. "They seem to anchor the skeletal structure!"

  Isolde, positioned near the back, felt the 'presence' spike – a wave of cold calculation directing the attack. She saw one of the Blighted Duergar deliberately trying to force Edmund towards an unstable section of wall. "Edmund, the wall to your left!" she cried out.

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  She raised her staff, gathering a small thread of Essence, just enough for a binding ward to momentarily slow the creature nearest Borin. The effort sent a jolt of pain through her arm, making her gasp, but the ward held for a precious second, allowing Borin to land a crippling blow. Control, she reminded herself, fighting the dizziness. Efficiency.

  They defeated the ambushers, but the fight was harder, costlier than it should have been against such decayed foes. The intelligence guiding them was undeniable.

  Borin led them deeper, following signs of the last missing patrol towards a large excavation chamber marked on his map. The air grew hotter, thick with the smell of sulfur and decay. Strange, rhythmic clicking sounds echoed from within.

  As they cautiously entered the chamber – a vast space littered with abandoned drilling equipment and scaffolding – the clicking intensified. It came from dozens of the skittering bone-and-fungus creatures clinging to the walls and ceiling, their movements unnervingly synchronized.

  Suddenly, with a low groan, several heavy support beams near the chamber entrance, weakened by corrosive slime, gave way. Rocks rained down, partially blocking the exit.

  "It's a trap!" Edmund yelled, shoving Isolde further into the chamber as the ceiling near the entrance collapsed completely.

  Then, the clicking creatures dropped, not randomly, but in waves, focusing their assault. A swarm surged towards Edmund and the guards, burying them under a tide of snapping bone and tearing fungus. Another group, seemingly ignoring the fighters, scuttled directly towards Borin, who was examining a large, corrupted Duergar drilling machine dominating the center of the chamber.

  "Borin!" Isolde screamed. She saw the creatures swarming him, trying to pin him against the machine. He fought furiously, his pick a whirlwind, but their numbers were too great.

  Desperate, Isolde poured her will into her staff, not a blast of energy, but a pulse of raw, untainted life Essence – a dangerous gamble near so much corruption. The green light flared, causing the fungus on the nearest creatures to wither and retract momentarily, giving Borin an opening.

  But the effort, combined with the chamber's oppressive psychic energy, brought her to her knees, nausea overwhelming her. The Blight Mind reacted. She felt its cold focus snap towards her like a physical blow. The large drilling machine shuddered, corrupted runes etched onto its surface flaring. With a horrific screech of grinding metal, its massive drill bit pivoted, not downwards, but sideways – aiming directly at the kneeling, vulnerable Isolde.

  Time seemed to slow. She saw the corrupted metal point swinging towards her, felt the terrifying certainty of the Blight Mind's intent. She couldn't move, couldn't summon the strength to cast even the simplest ward.

  Suddenly, Lyraen was there. Moving with impossible Aelfen speed, they tackled Isolde, rolling them both behind a discarded ore cart scant moments before the corrupted drill slammed into the rock where she had been, shattering stone and sending sparks flying.

  Lyraen hauled Isolde behind the relative safety of the cart, their usually calm face tight with urgency. Edmund, having finally fought his way clear of the main swarm with the aid of the surviving Duergar guard (one had fallen to the skitterers), rushed towards Borin, who had managed to disable several more creatures but was now bleeding from multiple cuts.

  The clicking swarm hesitated, momentarily confused by the failed attack on Isolde and the unexpected resistance.

  "We need to pull back!" Edmund yelled, helping Borin fend off the nearest creatures. "Find cover!"

  Borin nodded grimly, leading them towards a partially collapsed side tunnel he spotted across the chamber. They made a fighting retreat, Edmund and the remaining guard covering their backs, Lyraen supporting the still-shaken Isolde. They reached the tunnel, Borin quickly assessing its stability before they ducked inside, rolling heavy rocks into place to create a temporary barricade.

  Silence fell, broken only by their ragged breathing and the distant, enraged clicking from the main chamber. They tended to their wounds in the dim lantern light.

  Borin grimly examined a fragment of chitin ripped from one of the skitterers. "Duergar bracing techniques," he muttered, pointing at the way the bone shards were fused. "It's incorporating our structural knowledge into its creatures."

  Isolde leaned against the tunnel wall, pale but resolute. "That… focus," she whispered, touching her head where the psychic pressure still lingered. "It targeted me. It knew I was the magic-user. And it used Duergar machinery as a weapon."

  The confirmation was chilling. This wasn't just adaptation; it was active learning, strategic targeting, and tool use.

  "This Blight Mind… its reach is growing," Lyraen stated, their voice losing some of its usual detachment. "Its intelligence is consolidating."

  "We have to find its core," Edmund said, his voice hard. "Cripple it before it grows stronger."

  Borin slammed a fist against the rock wall, his face a mask of cold fury. "Aye. Twisted our craft, used our kin… It resides somewhere deeper. Fed by the earth's heat, likely. Near the main geothermal vents." He looked at the others, his eyes burning. "We press on. Find the heart of this rot. And cut it out."

  The decision hung in the tense air. They were wounded, low on supplies, facing an enemy that was not only monstrous but intelligent and learning fast. But turning back was no longer an option. Kaelen's Deep, Mercia, perhaps the entire Isles, depended on stopping this festering consciousness before it fully awoke.