Joe Parrino
Devourer

As war rolls across the Cryptus System, another threat rises as necron overlord Anrakyr the Traveller seeks to awaken a tomb world – a goal that will lead him into a desperate alliance with the sons of Sanguinius.
Warhammer 40k
novella

Also in:
The Great Devourer: the Leviathan Omnibus
Shield of Baal
Alien Invasion: the Xenos Digital Collection