The construct crooned in its chains. The central rod that Harrow had somehow awled through its trunk was bowing dangerously. Gideon dove back into the affray of joint and gristle with her sword scything before her and, just as in the Response room, felt another presence slide into her mind like a knife into a pool of water. Her vision blurred out and something said in the back of her mind:
On your right. Eye level.
It wasn’t a voice, precisely, but it was Harrowhark. Gideon pivoted right, longsword held high. The first leg of the construct loomed before her, a weighty breadth of impenetrable bone, but the back of her mind told her: Wrong. Inch higher. Pierce.
Gideon rehefted the weight of her sword in her hands, steadied the pommel with the butt of one palm, and thrust it home. The bone was thinner here. Across her softened sight a light fizzed in and out of vision, the exact same corona of light that had happened a thousand years ago—a hundred thousand, a myriad of myriads—inside the first trial chamber. She pulled her sword free and the leg buckled.
Half a dozen tendrils came after her. They would have given her an interesting array of new airholes for speed, but a skeleton staggered out of the darkness and took most of the blows, jawbone crushed into powder as a tendril lashed open its skull. Another skeleton lurched in where its comrade had died—but this one dashed past Gideon, over to the glimmering wound she had carved into the leg, and it thrust its arm into the gash.
Then it melted. Gideon had a few seconds to watch as it sludged into shining silvery-white bone matter. With a little sizzle of evil-smelling steam, it shrouded the wound and the bottom of the leg in a lahar of hot bone gunge.
She tore her gaze away to skid beneath the heaving torso of the beast, narrowly dodging another few desperate tendrils, cutting her way through a damp nest of them as they unfurled and regrew themselves like the coils of a razor-sharp plant. The leg closest to her had found purchase on the floor with its dainty, sharp-capped foot, so much like the leg of an arachnid, and seemed to be in the process of levering the whole thing upright.
The back of her head said: It’s above you. Gideon slipped her grip down the handle of her sword, her forearm alarmed with the effort, tip wavering as the leg shifted and hesitated above her. The back of her head said: Now.
This one was harder. She didn’t have as much purchase. Gideon rammed her sword upward, getting a grip on the pommel and shoving into the limb again, as plates of bone splintered overhead and dried flakes of marrow spun down like confetti. The leg tumbled down like a cut tendon.
Yet another skeleton appeared next to her and, as she withdrew the sword, plunged into the shining gap. It too dissolved into the hot, foul muck that slid inside the construct’s body and enrobed the rest of the leg, dripping down into the floor, cooling rapidly. The hard shine of it and the suppressed agony of triumph in the back of Gideon’s head made her eyes water, and she was filled with a weird pride that was all her own. Holy s**t. Perpetual bone. Harrow had actually cracked it.

Gideon the Ninth - Act Four, Chapter Thirty-Six