A mingled scent of sea salt and spirit herbs hung thick in the air of the Eastern Sea Branch's hidden chamber. The spirit-gathering formation carved into the stone dais hummed with slow, steady rotation, its pale-blue spiritual energy drifting like wisps of morning mist. I sat cross-legged at the very eye of the formation, both palms wrapped tight around a crystalline jade vial. The amber liquid within — the Marrow-Cleansing Elixir — sloshed gently, releasing a fragrance beyond description. A single breath of it was enough to set the spiritual energy in my dantian stirring with eager life.

"Rookie, you sure about this? The stuff's a treasure, no argument there — but getting your marrow washed is like getting flayed alive. Don't come crying to your mama when the pain hits." The System Elder's voice rang out inside my mind. His phantom projection hovered at my shoulder, one translucent hand pinching the remains of a half-eaten bag of crispy noodles.

I drew a slow, deep breath, my gaze sweeping over the defensive runes etched into the chamber walls before settling back on the vial in my palm. Ever since the battle at Black Reef Island, my cultivation had stalled at the mid-stage Foundation Establishment bottleneck. The core essence in my dantian felt as though it had been smothered by a thin veil — no matter how I cycled the Tidal Decree, I could not push a single step further. This Marrow-Cleansing Elixir was the supreme treasure the System had awarded me after I drove back Jin San-Jia. Rumor had it the elixir could scour the sinew and bone and reforge the very foundation of one's Dao.

"Pain?" I curled the corner of my mouth and twisted the stopper free with one fingertip. "I've been scrapping my way through the cultivation world. You think a little pain scares me?"

The instant the Marrow-Cleansing Elixir touched my tongue, it was nothing like the savage agony I had braced for. Instead it flowed like snowmelt on a spring afternoon — warm, smooth, gliding from my throat all the way down into my dantian. That warmth carried an inexplicable gentleness; wherever it passed, my meridians felt as though they were soaking in heated water, indescribably comfortable. But the gentleness was a lie. In the next heartbeat, that same warm current erupted into ten thousand steel needles and drove them into every bone, every sinew, every corner of my body all at once.

"Ngh—!"

A stifled grunt tore from my throat. My body arched involuntarily, as though countless fire-serpents were thrashing and ramming through my meridians. The veins beneath my skin pulsed and bulged visibly, and black impurities seeped from my pores, trailing a raw, rancid stench. This was the marrow-cleansing and bone-tempering at work — scouring away the dross accumulated inside me, breaking apart every last shackle of my mortal flesh. Within my dantian, the pale-blue core essence shuddered violently, its color deepening at a pace visible to the naked eye: from pale sky-blue into a rich, fathomless indigo, dense as the heart of the deep ocean, the spiritual energy it radiated growing ever more refined and immense.

"Hold on! Circulate the Tidal Decree — guide the elixir through your meridians!" The System Elder's voice grew sharp and urgent, his phantom projection flickering before my eyes.

I clenched my jaw and forced the technique into motion. Tidal waves of spiritual power surged and crashed through my body, resonating with the force of the Marrow-Cleansing Elixir. My meridians, once sluggish and half-blocked, were flushed clean by the elixir's current — like silted channels suddenly dredged open — and became unobstructed as they had never been before. My bones let out soft, rhythmic cracks; muscle fibers emitted faint, sharp pops as they tore and rebuilt themselves. With every breath, I felt the spiritual energy of heaven and earth pour frantically inward, transmuting into pure, refined spiritual power.

I do not know how much time passed. When the last trace of impurity was expelled from my body, my eyes snapped open. The world before me seemed sharper than it had ever been. The finest details of the runes on the chamber walls, the exact currents of spiritual energy flowing through the formation array, even the rhythm of distant waves breaking on the sea's surface miles away — all of it stood before me in perfect clarity. I could sense it plainly: the spiritual power within my dantian had become a vast, surging ocean, boundless and inexhaustible. The mid-stage Foundation Establishment bottleneck — under the Marrow-Cleansing Elixir's overwhelming force — had been shattered as easily as paper.

Ding! Congratulations, Host. Consumption of the Marrow-Cleansing Elixir complete. Fleshly body strength elevated to peak late-stage Foundation Establishment! Spiritual root quality optimized — current grade: Superior Water Spiritual Root!

Ding! Realm breakthrough! Current realm: Late-Stage Foundation Establishment!

The System notifications chimed one after another. I tightened my fist, feeling the raw power surging through me. I threw a single punch. The air cracked like a thunderclap. Several zhang away, a solid black-iron target plate used for testing split open with a web of fine, dense fractures. This was not the strength of a mid-stage Foundation Establishment cultivator. At this very moment, my fleshly body had quietly touched the shadow of early Core Formation.

"Fellow Daoist Ethan — are you all right?"

The stone door of the chamber swung quietly open, and Everett Li and Marcus Su stepped inside. Everett Li wore his customary cyan robe, jade-bone folding fan turning lazily in one hand; Marcus Su was wrapped in a scarlet law-robe, the flame whip at her waist trembling faintly. The two of them had clearly been waiting outside this whole time. Now, catching sight of the sweeping spiritual energy radiating from my frame, a flicker of undisguised surprise crossed both their eyes.

Everett Li's gaze landed on the tide-sword marking on my forearm — glowing now with the deep brilliance of a sapphire — and he exhaled in admiration. "Fellow Daoist Ethan, that sword marking of yours… it shines as though it has taken on physical substance."

Marcus Su stepped a few paces closer, reaching out with her senses toward the spiritual energy pulsing off me, and clicked her tongue. "Fellow Daoist Ethan, your cultivation speed is truly… terrifying."

I rolled my wrist. Driven by spiritual power, the tide-sword marking blazed brighter still. A faint wave of spiritual perception radiated outward from me as its center — and I could dimly see the spiritual energy signature of a fishing vessel on the sea surface ten li away. I could even tell which of the fishermen aboard was physically the strongest.

"Luck, nothing more," I said, tamping down the excitement rising in my chest, and folded my hands in a respectful bow. "All thanks to the Marrow-Cleansing Elixir retrieved from Jin San-Jia."

End of Chapter 75: The Marrow-Cleansing Elixir