The first possessed Space Marine had one of its freakish hands clutched around Bjorn's helmet, the other pinned his arms to his sides in an enwrapping embrace. The daemonic Space Marine was incredibly strong. A tocsin pinged in Bjorn's ear as the ceramite of his armour creaked under the pressure, then cracked. Gas hissed from the hole. His helm groaned and gave, the inner surface pressing into his scalp.

Bjorn grunted, and flexed his arms. The possessed Space Marine's pinning limb tightened like a constricting serpent around him, but in the moment before, it loosened a fraction, enabling Bjorn to swivel up the barrel of his gun.

His chest vibrated with the explosions of a dozen bolts as he emptied his weapon under the warped breastplate of his foe. It shrieked and fell away, curling up like a dead spider, leaving Bjorn panting and covered in smoking ichor.

The pain of the half-crushed helm became impossible to ignore. Bjorn swore as he fiddled with the release bolts. Still cursing angrily he wrenched it off and threw it away. His braids came loose, snagged on the ruptured ceramite, and his black hair stuck to the sweat of his forehead.

The battle was shifting. He looked up the hall to where the primarchs clashed. An inferno burned around the stairs, drapery and artworks falling in flaming swags to the ground.

Leman Russ was lying injured by the wall. Horus was pushing himself to his feet, retrieving his maul. He was wounded too, but he had won.

Bjorn felt a terror he had never known, not even as a youth fighting to survive the endless dangers of Fenris.

The primarch was going to die.

'To the primarch!' a voice called. 'To the primarch!' Warriors abandoned their individual struggles with Horus' traitors, felling their opponents in their desperation to get to their gene-father. Dozens failed and were cut down as they attempted to disengage and rush to the Wolf King.

They ran at the Warmaster, hitting him with weapons that had little chance of wounding him, grabbing for his arms. They were like children trying to save their parents from an ogre, helpless against his strength. They persisted, dragging at him with their weight of numbers. He bludgeoned them aside, killing one with every stroke. Jarls fell as easily as warriors.

Under the cover of their assault, Russ dragged himself away. Horus disappeared for a moment under a seething mass of grey ceramite warsuits, before he burst outwards, sending the Vlka flying. The survivors got up and hurled themselves back into the fray. Horus levelled the guns attached to his talon at them, blasting them down, but more came. Hundreds of the Vlka Fenryka sacrificed themselves to save their primarch. The Sons of Horus were forming up around their master, adding their guns to the culling of the Wolves.