Age of Darkness (The Horus Heresy, #16)

After the betrayal at Isstvan, Horus begins his campaign against the Emperor, a galaxy-wide war that can lead only to Terra. But the road to the final confrontation between father and son is a long one – seven years filled with secrecy and silence, plans and foundations being formed across distant stars. An unknown history is about to be unveiled as light is shed on the darkest years of the Horus Heresy, and revelations will surface that will shake the Imperium to its very foundation...

Rules of Engagement - Graham McNeill
https://www.goodreads.com/book/show/2...

Liar's Due - James Swallow
https://www.goodreads.com/book/show/2...

Forgotten Sons - Nick Kyme
https://www.goodreads.com/book/show/2...

The Last Remembrancer - John French
https://www.goodreads.com/book/show/2...

Rebirth - Chris Wraight
https://www.goodreads.com/book/show/2...

The Face of Treachery - Gav Thorpe
https://www.goodreads.com/book/show/2...

Little Horus - Dan Abnett
https://www.goodreads.com/book/show/2...

The Iron Within - Rob Sanders
https://www.goodreads.com/book/show/2...

Savage Weapons - Aaron Dembski-Bowden
https://www.goodreads.com/book/show/2...