Warhammer 40k - Horus Heresy Novella - The Seventh Serpent by Graham McNeill

The crew of the Sisypheum, Iron Hands, Raven Guard and Salamanders survivors, seek to strike a decisive blow against the Traitor Legions. Their target: a heavily defended Alpha Legion outpost.

Aided by some unlikely allies, they take their vengeance against the Sons of Alpharius. But as with anything involving the XX Legion, what awaits them on the station is not what they expect, and as the true architect of the battle reveals himself, the warriors of the Shattered Legions face a deadly opponent unlike any other.