Puzzled, she looked up in time to see the Warmaster's eyes roll back in their sockets and his legs buckle beneath him. She screamed, reaching out with her hand towards him, knowing that she was powerless to help him, but needing to try to prevent his fall.

Like a slow moving avalanche or a mountain toppling, the Warmaster collapsed.

The mnemo-quill scratched at the data-slate and she wept as she read the words there.

I was there the day that Horus fell.

From here, he could see the pyramid roof of the Amenaeum, die low evening sun reflecting on its gold panels as if it were ablaze, and even though Magnus knew he used but a colourful metaphor, the very idea gave him a pang of loss. To imagine that vast repository of knowledge lost in the flames was abhorrent and he turned his Cyclopean gaze from the pyramid of crystal glass and gold.

Tizca, the so-called City of Light, stretched out before him, its marble colonnades and wide boulevards tree-lined and peaceful. Soaring towers of silver and gold reared above a city of gilded libraries, arched museums and sprawling seats of learning. The bulk of the city was constructed of white marble and gold-veined ouslite, shining like a bejewelled crown in the sun. Its architecture spoke of a time long passed, its buildings shaped by craftsmen who had honed their trades for centuries under the tutelage of the Thousand Sons.

From his balcony on the Pyramid of Photep, Magnus the Red, Primarch of the Thousand Sons, contemplated the future of Prospero. His head still hurt from the ferocity of the nightmare and his eye throbbed painfully in its enlarged socket. He gripped the marble balustrade of the balcony, trying to wish away the visions that assailed him in the night and now chased him into the daylight. Mysteries of the night were revealed in the light of day, but these visions of darkness could not be dragged out so easily.

For as long as Magnus could remember, he had been cursed and blessed with a measure of foresight, and his allegorical interpretation of the Athanaeum ablaze troubled him more than he liked to admit.

He poured himself some wine from a silver pitcher, rubbing a copper-skinned hand through his mane of fiery red hair. The wine helped dull the ache in his heart as well as his head, but he knew it was only a temporary solution. Events were now in motion that he had the power to shape and though much of what he had seen was madness and turmoil, and made no sense, he could make out enough to know that he had to make a decision soon - before events spiralled out of control.

Magnus turned from the view over Tizca and made his way back inside the pyramid, pausing as he caught sight of his reflection in the gleaming silver panels. Huge and red-skinned, Magnus was a towering giant with a lustrous mane of red hair. His patrician features were noble and just, his single eye golden and flecked with crimson. Where his other eye would have sat was blank and empty, though a thin scar ran from the bridge of his nose to the edge of his cheekbone.

Cyclopean Magnus they called him, or worse. Since their inception, the Thousand Sons had been viewed with suspicion for embracing powers that others were afraid of. Powers that, because they were not understood, were rejected as being somehow unclean: rejected ever since the Council of Nikaea.

Magnus threw down his goblet, angry at the memory of his humbling at the feet of the Emperor, when he had been forced to renounce the study of all things sorcerous for fear of what he might learn. Such a notion was surely ridiculous, for was his father's realm not founded on the pursuit of knowledge and reason? What harm could study and learning do?

Though he had retreated to Prospero and sworn to renounce such pursuits, the Planet of the Sorcerers had one vital attribute that made it the perfect place for such studies - it was far from the prying eyes of those who said he dabbled with powers beyond his control.

Magnus smiled at the thought, wishing he could show his persecutors the things he had seen, the wonders and the beauty of what lived beyond the veil of reality. Notions of good and evil fell by the wayside next to such power as dwelled in the warp, for they were the antiquated concepts of a religious society, long cast aside.

He stooped to retrieve his goblet and filled it once more before returning to his chambers and taking a seat at his desk. Inside it was cool and the scent of various inks and parchments made him smile. The wide chamber was walled with bookshelves and glass cabinets, filled with curios and remnants of lost knowledge gleaned from conquered worlds. Magnus himself had penned many of the texts in this room, though others had contributed to this most personal of libraries - Phosis T'kar, Ahriman and Uthizzar to name but a few.

Knowledge had always been a refuge for Magnus, the intoxicating thrill of rendering the unknown down to its constituent parts and, by doing so, rendering it knowable. Ignorance of the universe's workings had created false gods in man's ancient past, and the understanding of them was calculated to destroy them. Such was Magnus's lofty goal.

His father denied such things, kept his people ignorant of the true powers that existed in the galaxy, and though he promulgated a doctrine of science and reason, it was naught but a lie, a comforting blanket thrown over humanity to shield them from the truth.

Magnus had looked deep into the warp, however, and knew different.

He closed his eye, seeing again the darkness of the corrupt chamber, the glitter sheen of the sword, and the blow that would change the fate of the galaxy. He saw death and betrayal, heroes and monsters. He saw loyalty tested, and found wanting and standing firm in equal measure. Terrible fates awaited his brothers and, worst of all, he knew that his father was utterly ignorant of the doom that threatened the galaxy.

A soft knocking came at his door and the red-armoured figure of Ahriman entered, holding before him a long staff topped with a single eye.

'Have you decided yet, my lord?' asked his chief librarian, without preamble. 'I have, my friend,' said Magnus.

'Then shall I gather the coven?'

'Yes,' sighed Magnus, 'in the catacombs beneath the city. Order the thralls to assemble the conjunction and I shall be with you presently.'

'As you wish, my lord,' said Ahriman.

'Something troubles you?' asked Magnus, detecting an edge of reticence in his old friend's tone.

'No, my lord, it is not my place to say'

'Nonsense. If you have a concern then I give you leave to voice it'

'Then may I speak freely?'

'Of course,' nodded Magnus.

'What troubles you?'

Ahriman hesitated before answering. 'This spell you propose is dangerous, very dangerous. None of us truly understand its subtleties and there may be consequences we do not yet foresee.'

Magnus laughed. 'I've not known you shirk from the power of a spell before, Ahriman. When manipulating power of this magnitude there will always be unknowns, but only by wielding it can we bring it to heel. Never forget that we are the masters of the warp, my friend. It is strong, yes, and great power lives within it, but we have the knowledge and means to bend it to our will do we not?'

'We do, my lord,' agreed Ahriman. 'Why then do we use it to warn the Emperor of what is to come when he has forbidden us to pursue such matters?'

Magnus rose from his seat, his copper skin darkening in anger. 'Because when my father sees that it is our sorcery that has saved his realm, he will not be able to deny that what we do here is important, nay, vital to the Imperium's survival!'

Ahriman nodded, fearful of his primarch's rage, and Magnus softened his tone. 'There is no other way, my friend. The Emperor's palace is warded against the power of the warp and only a conjuration of such power will breach those wards.'