Another shudder passed up the Pride of the Emperor. The rune denoting the strike against the enginarium turned green. Corvo would be pulling his Chapter back.

‘You can run now, if you want,’ said Fulgrim. ‘I believe your warriors have accomplished what you sent them to do. This vessel cannot pursue you. Some of you might even live. I do not care. All of you will bow before Slaanesh before the end.’

‘Enough!’ said Guilliman. He drew the Gladius Incandor in his right hand. The Hand of Dominion sparked into life on his left, an oily field of blue light encasing its massive robotic fingers and underslung boltguns. Raising the flat of his blade to the muzzle of his helm, he saluted his brother. He thumbed a switch, and a sheath of energy covered the blade to match that of his fist.

‘You are staying?’ said Fulgrim. ‘No dramatic teleportation? No strategic withdrawal? You actually want to fight someone you cannot hope to beat? Well, well, well, you are beginning to surprise me, Roboute. I never thought you had it in you. Perhaps you are not so boring after all.’

‘Honour demands I slay you.’

Fulgrim stretched out his arms. Blades rose from nothing, sprouting from his clenched fists, black vapours boiling off their metal as they were forced into being. The swords were mismatched in form, and every one a different pastel hue. Bright poisons dripped from their edges.

‘Honour will get you killed.’ Fulgrim raised his own blades to his face, the edges ringing off one another. There was no mockery to the salute. ‘So it is, brother. We come to the end. With you dead, our other brothers will follow, one by one. The Imperium cannot last without your guidance. It is you who holds the whole crumbling thing together.’ He smiled sadly. ‘Dull as you are, you were among the best of us. I almost feel sorry to kill you, if only because you will not see the triumph of the true powers of the universe, and know the liberation they bring.’

Swift as a striking viper, Fulgrim attacked, all four blades driving down at his brother primarch so quickly that they did not seem to pass through the intervening air. Guilliman caught them on the edge of the Gladius Incandor. Its field generator smoked at the effort of halting them. The resulting eruption of energy threw both primarchs backwards.

Fulgrim attacked again. Guilliman cried out as one blade found its way past his parries and left a smoking groove in the ceramite around his left arm. He would not win this fight.

‘Thiel, Andros,’ voxed Guilliman. ‘Now.’

There was a sound like a sigh that turned into a rumbling groan. The Heliopolis boomed with conflicting resonances, and the Phoenix Gate exploded inwards, showering the room with gobbets of molten bronze. The Ultramarines of the First and Second companies came charging in, bolters firing at the daemon primarch battling their lord.