This is yet another Space Marine Battles book. As usual, you can expect masses of fights, battles and gore, what we fans of Warhammer 40K usually call affectionatly "bolter porn". There is however much more to it than these basic ingredients that you generally find in almost all 40K books.
The main merit of this book, in my view, is that it is rather original in several respects.
The first original aspect is the choice of hero (or should I have said the "anti-hero"?). This is one Zachariah Kersh, Champion of the Excoriators Chapter, a successor chapter of Rogal Dorn's Imperial Fists. Despite being dishonored for failing to protect his Chapter Master (who was badly wounded and is slowly dying as a result) and for losing the Chapter's standards, he is their only chance for winning the Feast of Blades, a brutal contest between champions of all Imperial Fists successor Chapters that normally happens every 100 years. You can guess what happens. He is promoted to Captain of what is left of the Excoriators 5th Company, which is reduced to about half its strength and blames him for its troubles and he is despised as a result. Up to now, disgraced "anti-heroes" were mostly confined to "Traitor" Space Marines, with Talos of the Night Lords from Aaron Demski-Bowden being the prime example I can think of with regards to Space Marines (as another reviewer alludes to, there is, of course, the sase of Redemption Corp, also from Rob Sanders, but this book is not about Space Marines). This is the first example that applies to a (loyal) Space Marine. Although some could argue that Uriel Ventris the Ultramarine also fits the bill, this is not quite correct since the reader knows that his disgrace is unfair from the beginning. Kersh, on the contrary, seems to have deserved every bit of it, and most, if not all, of his brothers agree on this and despise him as a result.
A second trait which I very much appreciated, although it may perhaps not be entirely original, is Kersh's character and personality: he is the ultimate and relentless survivor, the one who never gives in and fights on, however battered, so that he is always the last man standing. There seems to be no thirst for glory or righteousness in him, just a grim determination to prevail through attrition, whatever it takes to do so. Despite the scorn that his brothers express, he seemed, at least to me, to be the embodiment of the Excoriators' virtues: grim, relentless, bleak with self-imposed sufferings to relive and atone for their primarch's long ago failure to protect the Emperor from Horus.
Another nice twist is the way that Rob Sanders has chosen to tell the story. He obviously has also taken a leaf out of Dan Abnett's hat. Where the latter chose to tell his story in Know No Fear using the format of a military report, Rob Sanders has preferred to make his entire (well, almost entite) book into a huge flashback. We hadn't seen either format before the respective books were published. So, the book begins as an Approbator of the Inquisition walks accross the so very gory battlefield of Certus Minor, a minor planet and a cemetery world, after it has been attacked by the Cholercaust, a war host of the Ruinous Powers spearheaded by berserk World Eaters Space Marines. The Approbator learns that there is a surviving Adeptus Astartes... Needless to say, the book also ends with this survivor, the Approbator, and a few others, with a few nice twists.
Yet another engaging and original feature is Sanders' treatment of the Legion of the Damned, as you will see for yourself when reading the book - sorry, I can't say much more here without providing spoilers. I can only say that it was not at all what I expected.
There was just one - relatively minor - element, at times: the treatment of the Cholercaust's troops felt a bit like a caricature, at times. Although I loved the descriptions of some of the monsters involved, you wonder how The Pilgrim or any of his lieutenants could plan any kind of planetary assault since they all seemed completely crazy and berserk all the time. This made me wonder and felt rather unrealistic but then, perhaps they didn't plan anything and didn't need to anyway since their armada was following the trail of the Keller Comet...
Another great read worth a good four stars.