Kletos swung his chainsword against the Word Bearer’s back. Mechanised teeth ground through the armour. The Word Bearer hurled Hierax down and whirled, striking Kletos a blow that knocked him back against the triforium’s balcony, then turned on Hierax again.

The Destroyer was already on his feet. He slapped a melta bomb to the creature’s chest plate. The fiery eyes flickered with dawning comprehension. The claws hesitated. Hierax crouched low, and his auto-lenses clicked shut against the flare of the blast. Damage runes flashed warning as the heat washed back over him, further disintegrating the wall. The full force of the explosion went through the Word Bearer. An inhuman thing shrieked. The sound took too long to fade, as if whatever had screamed were falling into an abyss beyond the materium. A pool of molten armour and charred fragments of bone lay where the Word Bearer had been.

Hierax lunged out of the ruined wall, guns in hand once more. The death of the monster had killed another Word Bearer, and the traitor’s squad had retreated a few yards, laying down heavy suppressive fire. The forwards doors of the fane burst open, and reinforcements poured in. The Destroyers had survived the ambush, but their advance was stymied.

‘Venerable Brother Antalcidas,’ Hierax voxed, ‘two missiles to the forwards doors. Destroyers, pull back and take cover.’

The rockets streaked from the Dreadnought’s Aiolos launcher. Hierax grinned tightly as they roared across the fane and exploded just past the altar, blasting the eight-pointed star to shrapnel.

‘Burn,’ Hierax muttered. ‘Burn, you treacherous scum.’

The missile warheads were phosphex shells. A cloud of burning mist erupted at the far end of the fane. Currents roiled within it as streamers latched on to the movement of the Word Bearers. It crawled over them, covering them in the white-green flame. The cloud billowed down the central aisle and along the triforia. It moved like a living thing, leaping and crawling over its prey. It burned armour, stripping it away layer by layer until it devoured the flesh beneath. The Word Bearers’ barrage faltered as the phosphex cloud moved down the forwards half of the fane, a grasping hand of agonised death. The traitors tried to escape. Many stumbled blindly, human torches of chemical fire, and spread the horror with them.

In the triforia and in the central aisle, the Destroyers formed a black wall. With bolter and plasma fire, they drove the Word Bearers­ back into the phosphex and cut down those who staggered out.

‘Scorch this hall,’ Hierax ordered.