The yellow-green fog hung over the Black Fen like a poisoned ceiling. But beneath it, the water was obeying the cold laws of fluid dynamics.
Along the two-mile defensive outer edge, the stone dykes stood twenty feet high, their upright granite faces clad in the slippery, diamond-smooth cobalt blue heat-proof glass glaze.
To an attacking monster, scaling a twenty-foot sheer wall coated in zero-drag glassy glass was a clockwork impossibility.
There was only one opening in the entire defensive outer edge: the great entrance to the Southern Drainage Canal.
Here, Sluice Gates Three and Four formed a twenty-foot-wide gateway of heavy white oak. He held back eight feet of rushing swamp water.
Giles Croft stood on the upper narrow high walkway of Sluice Tower One, wearing his tin snout breathing mask and his dark-tinted goggles, holding a brass stopwatch in his hand.
“The natural pathfinding logic of low-intelligence swarm entities is strictly cost-minimizing,” Giles said, his voice muffled by the charcoal canister. “A beast moving through marshland will always prioritize moving water over dry land, and an open chute over an upright obstacle.
We don’t need to lure them with bait. We lure them with high-pressure slope.”
Master Caleb Thorne-Wood stood beside the massive cast-iron crab-winch, his hands gripping the brake bar.
Connected to the winch were four heavy wrought-iron chains, each links three inches thick, leading down through greased pulley wheels to the lower oak gates.
“The head behind these gates is eight feet, Lord Giles,” Caleb called out over the roar of the water.
“If I drop the pawls and let the gates lift, thirty tons of water will dump into the canal race in thirty seconds. It’ll create a whirlpool that could suck down an ox-cart.”
“That’s exactly what we want,” Giles replied. “A sudden, high-speed intake current. Raise both leaves to the four-foot mark, Caleb. Open the funnel.”
Caleb threw the release lever.
CLANK-CLANK.
The iron ratchet screamed as the balance weights plummeted into their timber wells.
The two huge oak gates lifted smoothly along their upright bronze guide slots. They rose four feet above the doorstep stone.
The water of the Black Fen didn’t merely flow.
It was seized by gravity.
With an ear-splitting, cavernous roar that shook through the foundation piers of the tower, thirty thousand cubic feet of stale marsh water surged beneath the oak gates.
The sudden drop in deep water pressure created a massive, swirling drawdown funnel across three hundred yards of the outer marsh.
Rafts of floating reeds, dead willow branches, and thousands of gallons of foul peat muck were sucked into the narrowing vortex, churning through the concrete gates in a foaming, muscular rapid that sped up down the canal at more than six feet per second.
Chieftain Torvald Dune-Strider stood upon the low roof wall beside Giles, his twin willow-and-copper dowsing wands held out over the foaming chute.
The wands shook with such violence that the copper wire hummed like an insect swarm.
“The song of the hollow,” Torvald whispered through his tin snout. His amber eyes were wide with fierce admiration. “The water calls to the deep marsh like a running deer.
Every crawler, every hound, every leaper in the fens knows the sound of a draining pool! They think the world’s belly has cracked open!”
He pointed his wand toward the yellow fog.
Through the swirling sulfur mist, half a mile out in the marsh, the black water was moving.
A thousand V-shaped wakes broke across the stale surface.
The vanguard of Hesketh’s horde—four thousand hard-shelled mire-hounds and spiny leech-crawlers—had hit the suction current.
Their primitive hunting instincts, hardwired over thousand years of marsh survival, told them that rushing water led to dying fish and trapped prey.
They didn’t turn toward the sheer, slippery blue dyke walls.
They didn’t try to scale the jagged pine abatis.
They turned as one monstrous, writhing black wave, following the rushing current straight into the mouth of the concrete canal hall.
The shape of the canal cut had been engineered specifically for holding.
The channel was not a crude dirt ditch with crumbling mud banks.
It was a trapezoidal concrete water chute, twenty feet wide at the bottom, thirty feet wide at the crest, with forty-five-degree sloped stone retaining walls paved in linked volcanic cement concrete slabs.
The upper four feet of the embankment were clad in the glassy cobalt blue heat-proof glass tiles that offered zero purchase to claws, talons, or climbing spines.
Master Duncan Stone-Splitter stood on the access narrow high walkway above the gate pier. He watched the water churn through the water gate.
“A ditch with walls slicker than greased ice,” Duncan said, resting his hand on the massive iron pivot pin of the gate. “If a man fell in there, he’d need a rope to get out.
For a beast with claws, it’s a funnel with no lid. They can run forward, or they can drown in their own filth.”
“The design follows standard water chute hydraulics,” Giles noted, checking the clearance with his rule.
“A trapezoidal channel maintains a high-pressure radius, maximizing speed while minimizing frictional boundary layer drag. The water moves fast. The entities move with the water.”
“Mob pathfinding locked,” Giles observed, clicking his stopwatch. “Target flight path aligns with the canal axis to within three degrees. They’re marching into the funnel with eighty-five percent posture smooth speed.”
Captain Kenneth Drake marched up the narrow high walkway, his broadsword resting in its sword sheath, his hand resting on the handle of his trenching rod.
“They’re taking the bait,” Kenneth said, peering through the slits of his leather cap. “Look at them pour in.
Three hundred beasts through the gates every minute. The ditch is packing solid from bank to bank.”
“It isn’t bait,” Giles said calmly. “It’s fluid mechanics. Nature abhors an empty pocket, and low-tier mobs abhor climbing upright obstacles when a clean canal hall is available.”
He turned toward Toby Karr, who stood beside the speaking-tube connected to the four rail batteries along the dyke.
“Toby, notify Batteries Alpha through Delta,” Giles commanded. “Hold fire on all light infantry.
Don’t waste heavy metal dart rounds on mire-hounds or leech-crawlers. The rail-lances are reserved only for armor-class titans exceeding fifteen feet in height.”
Toby spoke into the copper tube with crisp power: “All batteries hold fire! Conserve star-iron! Target priority is titan-class only!”
Down along the canal hall, the sight was nightmarish.
The twenty-foot-wide concrete channel was turning into a boiling river of black hard shell, clicking jaws, and thrashing barbed tails.
Four thousand mire-hounds—six-legged amphibious hunting beasts with curved bone fangs and armored dorsal plates—surged down the waterway, swimming and scrambling through the shallow current at twenty miles per hour.
Behind them came two thousand leech-crawlers. Bloated, armored abominations as thick as barrels, their segmented bodies bristling with poisonous spines that cried yellow acid into the foam.
The high concrete banks and glass-fused blue coping tiles kept them trapped.
Every time a mire-hound tried to leap from the channel, its claws slid helplessly off the zero-drag blue heat-proof glass enamel. It sent the beast tumbling back into the churning mass of its fellows with a wild hiss.
They were channeled into a straight, inescapable killing hall, thirty paces wide. They were flanked by twenty-foot sheer walls and overseen by four armored rail flatcars.
Maeve Swift-Ear stood on the lower firing step beside Kenneth Drake. Her brass ear-trumpet was pressed against her furred ear.
Her eyes suddenly widened in terror.
“Kenneth,” Maeve choked out through her snout mask, grabbing the Captain’s sleeve. “The sound... The big pulse is at Mile Marker Zero point eight! The ground is tearing open!”
A sudden, earth-shaking blast wave ripped through the canal floor half a mile downstream.
The concrete bed of the canal shuddered.
Out of the boiling water, rising like three huge, rainbow-bright black towers into the yellow fog, reared the three snake-like necks of the Three-Headed Rot-Hydra.
The monster was eighty feet long, its massive draconic torso clad in overlapping plates of high-hardness stone-hardened hard shell that cried green, smoking acid into the water.
Its three crested heads soared forty feet into the sky. Their jaws gaping was wide to reveal rows of jagged, yellow fangs dripping with skin-burning necro-bile.
Surrounding the titan hovered a shimmering, thirty-yard dome of brilliant emerald light—the legendary bio-arcane mana-shield of the Founding Age.
The Three-Headed Rot-Hydra had entered the concrete canal cut.
Rook Red-Mane leaned over the low roof wall. His yellow eyes tracked the monstrous shape moving through the center of the canal.
“Look upon her central crest,” Rook whispered, his voice trembling with hatred and fear. “There, between the horns of the middle neck!”
Giles raised his brass telescope, bringing the aiming cross onto the hydra’s central spinal junction.
Perched atop a platform of woven black bone lashed between the titan’s armored spine bones stood a figure draped in tattered, spore-stained vestments of dark green silk.
He held a staff carved from the thigh bone of a dragon, topped with a glowing, pulsating orb of dark purple fungus that pulsed with sickening bio-arcane light.
“Hesketh the Rot-Weaver,” Kenneth Drake growled. His knuckles turned white on the handle of his broadsword. “The Hierophant of the Black Mildew himself. He rides the beast like a field marshal.”
“A living command-and-control node in a raised, exposed vantage point,” Giles remarked clinically, adjusting the telescope focus.
“A severe tactical miscalculation. Placing the main organic intelligence on an unarmored saddle fifty feet above ground level makes him an ideal target for high-speed moving interdiction.”
Kenneth looked at Giles, blinking through his snout mask. “You mean... We can snipe the wizard?”
“He has a frontal cross-section of less than two square feet,” Giles said.
“At five hundred yards, a tiny heavy dark metal needle will pass through his chest cavity before his throat cords can complete a single magic chant. But first, we must stop the swarm vanguard.”
A low, gurgling roar of earth-shattering fury tore from its three throats at the same time. It shook the foundation stones of Sluice Tower One.
Giles Croft stood on the upper narrow high walkway. He looked down at the huge monster wading into the kill-box.
He pulled his wooden ruler from his pocket. He tapped it against his palm with steady, clockwork rhythm.
“Target thickness has reached ninety-eight percent of channel capacity,” Giles said. His voice was cold, steady, and fully rock-steady. “The kill-box is full.”
He stepped up to the brass master control levers, his gloved hand resting upon the trip-catch of the peat-tar channel.
“Toby,” Giles commanded. “Signal Sister Teresa. Sound the general engagement.”