The air in the southern polar mountains was thin and lung-bitingly cold, but it was a welcome change from the heat of Aghoru. Ahriman did not feel the cold, but the soldiers of the Prospero Spireguard were not so fortunate. To survive the sub-zero temperatures, they wore thick crimson greatcoats, heavy boots and silver shakoes, lined with fur cut from the wings of the snow-shrikes used by the Avenians as brutally effective line-breakers.

Ahriman, Hathor Maat and Phosis T’kar sat with three hundred Astartes attending to their wargear in the ruins of the mountain fortress. They cleaned their bolters and repaired chips in their armour while Apothecaries tended to the few wounded.

Dead Avenians littered the toppled battlements and shattered redoubts, a drop in the ocean compared to how many had died since the invasion of Heliosa had begun. Ahriman estimated they had killed close to three million of their warriors.

“Five thousand,” said Sobek, returning from tallying the dead.

“Five thousand,” repeated Phosis T’kar. “Hardly any. I told you there wasn’t as much of a fight in this one as the last.”

Phosis T’kar’s bolter floated in the air in front of him, the weapon disassembled and looking like a three-dimensional diagram in an armourer’s manual. A cleaning cloth and a vial of lubricating oil moved of their own accord through its parts, guided by Phosis T’kar’s Tutelary. The faint glow of Utipa formed a haze around the components, as if a ghostly Techmarine attended the gun.

Hathor Maat’s weapon sat next to him, gleaming as though lifted fresh from the sterile wrapping of a packing crate. He had no need to even strip down his weapon, and simply disassembled the molecular structure of the grease, dirt and foreign particles from the weapon’s moving parts with the power of his mind.

Ahriman worked a wide-bore brush down the barrel of his bolter, enjoying the tactile, hands-on approach to weapon maintenance. Aaetpio hovered at his shoulder, but he had no wish to employ his Tutelary for so menial a task as cleaning his bolt gun. It was too easy to forget that while ensconced in one of the expedition fleet’s many libraries or meditating alone in an invocation chamber.

In the six-week journey to the Ark Reach Cluster, Ahriman had spent much of his time with Ohthere Wyrdmake, the Rune Priest proving to be an entertaining companion. Though the terms they used for their abilities were very different, they found they had more in common than either of them had imagined.

Wyrdmake taught Ahriman the casting of the runes, and how to use them to answer vexing questions and gain insight into matters of inner turmoil. As a means of reading the future, they were a less precise method than those taught by the Corvidae, for their meanings required much in the way of interpretation. Wyrdmake also taught him the secret of bind-runes, whereby the properties of several different runes could be combined to draw similarly-attuned aetheric energies towards an object or person.

Wyrdmake’s chest and arms were tattooed with numerous bind-runes: runes for strength, runes for health and runes for steadfastness. None, Ahriman noticed, were for power. When he asked Wyrdmake about this, the Rune Priest had given him a strange look and said, “To speak of possessingpower is as foolish as saying you own the air in your lungs.”

In return, Ahriman taught the Space Wolf more subtle means of manipulating the energies of the Great Ocean. Wyrdmake was skilled, but his Legion’s teachings were tribal and violent in the drama of their effect. The calling of the tempest, the sundering of the earth and the rising of the seas were the currency of the Rune Priests. Ahriman honed Wyrdmake’s abilities, inducting him into the outer mysteries of the Corvidae and the rites of Prospero.

The first part of this was introducing him to the concept of Tutelaries.

At first, Wyrdmake had been shocked that the Thousand Sons employed such creatures, but Ahriman believed he had come to accept that they were little different from the wolves that accompanied the Space Wolves. Wyrdmake’s companion, a silver-furred beast named Ymir, had been less accepting, and whenever Ahriman summoned Aaetpio, the wolf howled furiously and bared its fangs in expectation of a fight.

Such secrets had never before been taught to an outsider, but Magnus himself had sanctioned Ahriman’s work with Wyrdmake, reasoning that if a Legion such as the Space Wolves could be turned into allies through understanding and careful education, then other Legions would surely present few problems.

Though Ohthere Wyrdmake was a frequent visitor to the Photep, Lord Skarssen preferred to keep to his own vessel, a lean, predatory blade named the Spear of Fenris.

“Do you want me to help you with that?” grinned Hathor Maat, displaying a perfect smile of brilliantly white teeth. His hair was dark today, his eyes a deep brown. Though his features were still recognisably his own, they had taken on a rugged look, as if mirroring the terrain they had so recently fought over.

“No,” said Ahriman. “I do not use my powers to accomplish things I can do without them. You should not either. When was the last time either of you used your hands to clean a bolter?”

Phosis T’kar looked up and shrugged.

“A long time ago,” he said. “Why?”

“Do you even remember how to do it?”

“Of course,” said Phosis T’kar, “How do you think I do this?”

“Spare us yet another ‘we shouldn’t rely too much on our powers’ lecture,” groaned Hathor Maat. “Look at what would have happened to us on Aghoru if we had followed your teachings. The primarch might have died without Phosis T’kar’s kine shield. And without my mastery of biomancy, T’kar certainly wouldbe dead.”

“As you’ve never let me forget,” grumbled Phosis T’kar.

“Astartes first, psykers second,” said Ahriman. “We forget thatat our peril.”

“Fine,” said Phosis T’kar, dismissing Utipa and bringing the components of his weapon to his hands. He slotted the gun back together with a pleasing series of metallic clicks and snaps. “Happy now?”

“Much happier,” said Ahriman, reassembling his own bolter.

“What’s the matter?” asked Hathor Maat. “Are you afraid your new friend will disapprove?”

Phosis T’kar spat over the edge of the rampart, his spit falling thousands of feet.

“That damned Wyrdmake shadows us like a psychneuein with the taste of an unguarded psyker in its mandibles,” he hissed, his anger fierce and sudden. “We could have won this war months ago but for the shackles you put on us.”

Phosis T’kar jabbed an accusing fist at the smoking remnants of the tallest peak of the mountain aerie.

“The primarch shows no such restraint, Ahzek, why should we?” he asked. “Are you so afraid of what we can do?”

“Maybe I am,” said Ahriman. “Maybe we all should be. Not so long ago, we hid our powers from the world. Now you use them like mere cantrips to save you getting your hands dirty. Sometimes it is necessary to climb down into the mud.”

“Climb down into the mud, and all you will get is muddy,” said Hathor Maat.

“Not much in the way of mud on this world,” said Phosis T’kar. “These aeries put up little fight. How this planet has held out for so long is a mystery to me.”

“The bird-warriors are stretched thinly now,” Hathor Maat pointed out. “The Wolves have seen to that. And what Russ and his warriors haven’t savaged, the Word Bearers have put to the flame. An entire mountain range was burned out with a saturation promethium bombing three days ago to cleanse the aeries that Ahzek and Ankhu Anen found.”

“Cleanse?”

“Kor Phaeron’s word,” said Hathor Maat with a shrug. “It seemed appropriate.”

Kor Phaeron was one of Lorgar’s chief lieutenants, and epitomised all that Ahriman disliked about the Word Bearers. The man’s mind was filled with zealous certainties that could not be shaken by logic, reason or debate.