My voice rang through the basin just as a bolt of steel and ball of fire struck the creature. Steam billowed from the wound and droplets of acid sprayed in every direction, pitting stone where they landed, but the creature did not shrink back.
It turned on us with an alarming speed, its bulk surging forth like a wave. Nox and I braced at the mouth of the corridor, our bodies forming the last wall as Annalise and Velyan retreated into the narrowing space behind us.
"There!" Velyan rose above the chaos, "It's core! The off blue-spot in the middle."
Another bolt whistled past my cheek, striking true. It punched through the membrane and vanished, melting away into nothing, but it showed me enough. A faint, darker patch deep within the mass, barely visible unless you searched for it.
I had no time to call it out. A portion of the slime lashed forward, shaping itself into a club the size of a tree trunk. It swung down at me with terrifying weight. I dropped into a roll and came up hard, my morning star smashing against its side. The blow ripped open a cavity, sending rivulets of acid sloshing out across the floor with a foul hiss, the air filling with the reek of burning stone. But the membrane sealed itself almost instantly, erasing the damage.
Then came a crushing impact. The club caught me on the side before I could recover, slamming me into the wall. Stone shattered at my back and something inside me gave way with it. Pain shot through my ribs like knives every time I drew breath. I staggered, the world swimming, and saw the mass reforming for another strike.
Nox darted in, her blades flashing silver. She cut through the outstretched limb, severing it before it could hammer me again. The dismembered mass splattered to the floor, acid splashing in angry streaks that burned through wall and stone alike.
Music surged behind me, Annalise's bow screaming across strings. The sound was raw, imperfect, and yet the magic inside it seeped into my body. A thread of strength wound itself through my bones. The pain was still there, but dulled, enough to keep me on my feet.
The slime pressed closer, filling the corridor until retreat was no longer possible. My morning star was already gone, swallowed whole by its body. I tore the longsword from my back, steel glinting in the lanternlight, and ripped a jagged wound through the creature's flank. Acid cascaded out like a waterfall, splattering across my arm and filling the corridor with the stench of singed leather. I hissed through my teeth, retreating just in time as the wound sealed.
Beside me Nox fought like a spirit born of the blade, her movements fluid and fast. She danced along the edge of the slime, steel tracing arcs of light in the gloom, cutting slivers from its body. It was beautiful and terrible all at once. But then the tide turned against her.
The slime surged forward with a suddenness that caught even her off guard. The clubbed limb came down low, too fast to dodge. Her arm disappeared into the mass, and then her shoulder, the slime swallowing her with horrible eagerness. Her scream tore through the corridor, raw and guttural, a sound that froze my blood.
For one sickening heartbeat I was paralyzed. All I saw was Nox's body half-consumed, her face contorted with pain, her free hand clawing at the air. Panic clawed at my throat. If I hesitated, she was gone.
Then Annalise's violin shrieked, the sound so sharp it rattled my teeth. The slime rippled, convulsing as if the music itself scalded it. I lunged into that single heartbeat of reprieve, grabbing Nox by the shoulder and wrenching her free. Her body tore loose, but one of her swords was gone, pulled deep into the monster's body.
"That's the last time I can do that!" Annalise cried, her voice ragged.
Dark magic slid across Nox's burned flesh, knitting it together with shadow. She staggered, still bleeding but alive. Relief hit me so hard it nearly buckled my knees, though there was no time to savor it. A bolt hissed overhead, striking another reaching limb and exploding it in a spray of hissing acid.
"Heal later, fight now!" I roared. My sword plunged deep, dragging a long tear through the creature. Acid licked at my hand, burning through leather. I pulled back, teeth clenched, as Nox rolled free and snatched her remaining blade.
"We don't have much room left," Velyan called, her voice strained.
A glance confirmed it. We had barely ten feet between us and the back wall. The beast still carried half its mass. Its core was still faintly visible, three arm-lengths deep within.
Then a silver light streaked past me, guided by Annalise's trembling hand on her violin. The note rang pure, and the core within the slime burned with a silver light.
"That's… is all I have left." Annalise whispered, slumping against the wall. Her body shuddered with exhaustion.
The slime lashed again. I ducked beneath its clubbed strike, dragging my sword across its length, then reversed my grip and carved another line across its hide. More acid poured out, this time burning a hole into the flagstones, but the wounds healed faster now, each tear closing almost as soon as it opened.
Then agony shot up my leg. I looked down. The slime had surged low, swallowing my foot whole. It climbed fast, rising to my knee before I could wrench free. I slammed my sword down behind me to use as leverage to escape, but the steel just sparked against stone.
The pull was relentless. It dragged me forward, the world narrowing into the desperate thrash of my arms. For an instant I felt the horrible weight closing over me.
Hands seized me beneath the arms and yanked. Velyan's face flashed in the corner of my vision as she hauled me free with a strength born of sheer will. We stumbled back, but my leg screamed and gave way. I fell across her, the two of us crashing to the stone.
The wall was five behind us now. Five feet left to live.
Annalise lay motionless, her lantern flickering beside her. Nox leaned against the stone, eyes closed as if resigned. Velyan struggled behind me to load another bolt, her fingers trembling. The core remained untouchable.
Valaris, if you are watching, give me the strength to stand and fight. I grabbed the wall and hauled myself up, looking for my sword. It was engulfed by the slime too. I had nothing left.
What could I do? How can I solve this? There had to be some way I could fix my mistake. I shouldn't have ushered us into a dead end. I was so stupid. If I could just go back in time and fix it.
And then the lantern sputtered to embers. Shadows thickened, gathering as if pulled from the ground and gathered around Nox. Around her sword.
The dark grew heavy, a tide of night drawn into a single line of steel. Nox raised it high above her head. Her voice fell into a guttural tongue I had never heard, each syllable scraping against the air like stone one stone.
She swung.
The shadows curved forward, a single stroke given form. The blade of night split the slime clean through, striking the glowing core and cleaving deeper, tearing a scar into the ceiling and the floor.
The creature shuddered. Its body split into two sagging halves and then collapsed altogether. The core cracked and vanished in a shiver of light. The remains sank swiftly into the vents, a river of acid vanishing into the sewer's hidden veins.
Silence held us. Only the hiss of the remaining acid on stone remained.
Nox stood with her sword lowered, her chest rising and falling with unsteady breath. Then her knees gave out. She collapsed forward, and I lunged, catching her before her head struck stone. My leg screamed, but I did not let go.
I eased her against the wall, away from the draining acid, and lifted my eyes to Velyan. She sat slumped, her chest heaving as if every breath was the last strength she had left. Slowly she slid down the wall until she sat beside me.