The Passing of Angels (The Horus Heresy: Primarchs)

A Primarchs story
When a non-compliant world unleashes heinous weapons, it falls to Sanguinius and his Destroyer Host to bring the planet into compliance – by any means necessary. READ IT BECAUSE
It's an insight into how the Blood Angels view the hideous acts they must perform in the name of the Imperium, and a look at the lengths to which Sanguinius will go to protect his sons.THE STORY
When a world resistant to the nascent Imperium of Man unleashes weapons of heinous and proscribed provenance, it falls to the Blood Angels to bring the planet to compliance. Forced to fight fire with fire, Sanguinius gathers the Legion's Destroyer Host and their deadliest weapons. As his sons wage war behind their death masks, able to leave the taint of their bloody deeds behind them, Sanguinius alone must bear the burden of the souls he has reaped.

This story is also available in the Sons of the Emperor anthology.