The prison had been built to hold almost anything.
Almost.
The roar that came through the breach was not the sound of an animal or a man. It was the sound of something that had moved beyond either category, a noise that started deep in a chest the size of a cargo container and expanded outward until it had no upper limit. The metal walls of the inverted pyramid shuddered with it. Pieces of the outer casing the thickness of a man's torso were flung away from the breach in fragments as the gap widened, each piece tumbling end over end through the pale pink air before it hit the ground.
Then the gamma light inside the breach brightened, and the thing that had made the roar stepped out into the open.
Seven meters tall. Skin the deep, saturated blue of something irradiated to its cellular core, every visible inch of it traced with the branching dark lines of gamma-engorged veins running beneath the surface. The body beneath was still barely recognizable as humanoid in its gross proportions, two arms, two legs, an upright posture, but the scale of it and the particular density of its mass put it firmly outside any normal frame of reference. The head was massive and round, covered with the same vascular web as the rest of the body, and the eyes it turned on the world were large, empty, and utterly without recognition.
But there was something else on that head. A second face, smaller, distorted, pressed against the blue skin as though trying to push through it from inside. The expression on it was unmistakably human, and unmistakably in agony, the features contorting and straining as though fighting to separate from the surface that contained it, then being pulled back, over and over, finding no escape.
The blue giant's enormous feet came down on the wet earth with impacts that left craters, and behind it, through the breach it had torn in the prison wall, the rest of what had been inside came flooding out.
The gamma monsters had been mutant criminals an hour ago. Now they were neither mutant nor criminal in any meaningful sense, just bodies reshaped by the radiation into driven, barely-controlled vectors of destruction, pouring through the gap in a tide, dozens and then more, their total number accounting for most of what the underground prison had held.
The Knight Dominus suits were already tracking.
Whirlwind missile salvos arced from their shoulder mounts in rapid succession, the contrails rising and curving before the warheads came down across the enemy mass in overlapping detonations, each one throwing up a column of fire and debris that merged with the next. The gamma monsters closest to the impacts were reduced to fragments. The ground between the prison and Nolan's position became a churning field of fire and falling metal.
At the center of it, the blue giant stood unharmed.
It turned toward the source of the bombardment.
Nolan did not hesitate.
"Knight captains, shift to long-range harassment and target suppression. Keep its attention divided. Everyone else, disperse. Bolter fire, mobile pattern. Do not engage it in melee."
He was already moving as he gave the order, the Dawnbringer coming up in both hands as he crossed the broken ground toward the blue giant at a run. The heavy hammer head connected with the side of the creature's torso with a crack that rolled across the entire ruins, the impact driving a shockwave outward through the visible pink air and tearing a wide section of blue flesh and bone fragments free of the giant's ribcage.
The creature staggered sideways.
From the flanks, arcing bolts of psychic lightning fell across the blue giant's body from the White Scars Stormseer, each discharge leaving a scorched channel across the blue skin that began closing almost before the bolt had finished.
Nolan watched through his helmet's eyepiece for two seconds.
"Stormseer, cease lightning. Immediately. This creature absorbs energy input to accelerate its own regeneration."
He pulled the Dawnbringer back and put it down. The weapon was devastating against things that stayed damaged. Against something that healed this quickly, a slow-cycle weapon was the wrong answer.
The Stormseer broke off his discharge and pushed a psychic barrier outward around himself.
It lasted approximately one second before the blue giant's fist hit it.
The barrier shattered. The Stormseer was airborne for the length of a practice field, tumbling end over end, before he hit the ground and rolled to a stop against a section of collapsed wall. He was alive. His armor's structural integrity had held. He did not get up immediately.
On the other side of the fight, one of the Raven Guard champions had used Shadow Step to move clear of a sweeping arm and almost made it. The giant's hand found his thigh at the edge of the teleport recovery window, fingers closing around the ceramite with the casual efficiency of something that did not need to try, and then the champion was flying, released at the top of a wide arc, crashing into the rubble field hundreds of meters away.
A White Scars battle-brother absorbed a kick to his chest and abdomen plating that buckled the entire front of his torso armor. The explosive decompression of the ceramite sent fragments in every direction as he was driven backward and off his feet.
Nolan raised both arms.
The Ten Rings responded, the ten metal loops rising from his gauntlets and accelerating into tight orbit around the skull helm before launching outward in a converging spread, each ring carrying enough kinetic force to punch through a vehicle hull. They struck the blue giant across its chest and shoulders and skull in rapid succession, the impacts overlapping, driving the creature back a step, then another. The rings reversed and struck again from the other direction, carving channels through the blue flesh that closed behind them even as new ones were being opened.
The giant's empty eyes locked onto Nolan.
It gathered itself and began to move toward him.
Then the sky opened up above them and the noise of a hundred chainswords starting simultaneously filled the air, a sound like a mechanical storm descending, and the Automata Corps hit the ground in a wave between Nolan and the blue giant.
They came down hard and fast and without hesitation, the Scyllax units and their heavier companions slamming into the rubble and driving forward immediately, chainswords cycling, hydraulic limbs driving them toward the blue giant at a pace that suggested something between a charge and a controlled collapse. They were not precise. They were not careful. They were a mass of metal bodies moving in the same direction at the same speed with the same complete indifference to their own structural continuity.
They hit the blue giant like a wave breaking against a seawall.
And the blue giant hit them back.