It wouldn't be a Warhammer 40k work without a healthy dose of nightmare-inducing visuals.
- To start with, the Astartes themselves. The Retributors' attack on the rebels is both awe-inspiring and terrifying. They operate with cold, calculating efficiency, killing enemy soldiers effortlessly, despite their very competent efforts to stop them. Unlike in other mediums featuring Astartes, the Retributors do not shout "For the Emperor!" or banter about during their assault. In fact, they don't speak at all, fighting in complete silence. They're more like machines than humans.
- The twin psykers are very frightening. They are almost the same height and build as the Astartes, wearing golden masks shaped into an effigy of a human face, but that's just the least scary aspect. Both of them boast telekinetic abilities that are potent enough to knock aside Space Marines with a single blast, catch bolter shells in midair and hold an Astartes in a psychic grip that he can only barely move in. They're the first real resistance the Retributors encounter, to the point that they have to use a whole other set of tactics to beat them. But the really scary part is that, all things considered, these two aren't actually that powerful in terms of psychic might.
- Part 5 is a grim reminder to the audience that as powerful as the Adeptus Astartes are, they are still near the bottom of the totem pole when it comes to the actual eldritch powers within the ship's vault. A mysterious orb that resists the Astartes attempts to contain it and drags them into itself. Every space marine unable to even move once they make contact, helpless to stop themselves being slowly absorbed by it. Not even a point blank plasma pistol shot is enough to stop it. The unfortunate marine who tries that gets his arm blown clean off for his trouble.