'He has boltguns, we have boltguns. He has void ships. We have void ships. We have Titans and cybernetica legions, fighter craft and Legiones Astartes. So does he. We have everything he has, and he has everything we have, apart from one weapon. A deadly weapon.' Kva tapped Valdor's engraved nameplate with the head of his staff. Bone trinkets jangled. 'Horus has magic. Real magic, drawn from the corrupt wellsprings of the Underverse. He has drunk deeply from black waters, its powers flow through his veins. We have the Emperor, but He is occupied. You did say this, did you not?' said Kva. 'He cannot be everywhere, as powerful and all-knowing as the Allfather is. Otherwise, why would He need His sons? Why would He need you?'

'Some would say you are a witch,' said Valdor.

'By that definition, so is Malcador, so is the Allfather. So are all those gifted men and women you use in this war against the foe. They are all witches, but you do not fear them. You use them. They are not the only ones to draw upon the powers of the Underverse without malice.'

'The Emperor vouchsafes the purity of their gifts. They are watched. You are not.'

Kva laughed. 'There is no purity in this power. All of it is touched by corruption. But a man's heart, or a world's, that can be pure. We Rune Priests know when to stop. Our gifts are formed from the ice and heat of Fenris' world forge. We know not to venture beyond these bounds.'

'So you know restraint?' said Valdor. 'You know better than the Emperor?'

'I trust these men,' said Russ. 'We are the executioners of the Emperor. Our ways of life and war are defined by knowing the limits, and punishing those who exceed them.'

'You didn't bring your priests to the surface,' pointed out Valdor.

'The Great Wolf is headstrong some days,' said Kva, 'but he isn't a fool.'

Russ grunted at Kva in acknowledgement.

'This conversation will go nowhere, Constantin. So tell me, have you come to drag me back down to the surface and denounce me in front of my father, wherever He is, or are you going to let me get on with the business of killing my brother? It's high time someone did.'

'I want you to think, my lord,' said Valdor.

'Who says I don't?' said Russ. He leaned down so that he was eye to eye with Valdor, and bared his pointed teeth in a feral grin. 'I'm a thinker, me. I'm known for it.'

'Yes, you are,' said Valdor without mockery. 'I have seen that fine mind of yours in action. Please remember, my lord, that Horus will not be fooled by your barbarian facade.'