the book is called PRIESTS OF MARS
Okay I think I can give a summary because the basic concept is pretty simple. There's this region of space called the Halo Scar, and a bunch of freaky stuff happens in it. Space beyond the Scar has never been charted. One fleet of Adeptus Mechanicus tried to traverse it thousands of years ago and never came back. But--wonder of wonders--a rogue trading group managed to pick up an ancient signal from that fleet. The Adeptus Mechanicus view this as a sign from their god, the Omnissiah, that the time is ripe to try and cross over into that unknown territory again. Knowing the journey will be risky, they set out in a powerful and ancient ship, the Speranza, along with the rogue traders, military, elite guards, and god-mechs.
THE CAST - groups
Adeptus Mechanicus: Think Vulcans on steroids. Their physical bodies are highly augmented, if not completely artificial. They live thousands of years. They communicate amongst themselves in "blurts of binary," as they believe it to be more accurate and concise than language spoken with their "flesh voice."
Main characters: Lexell Kotov (expedition leader)
Rogue traders: I don't think this concept needs explanation.
Main characters: Roboute Surcouf (captain)
Black Templars: A crusading chapter of the Space Marines. Elite warriors who focus on success and domination in battle.
The Cadian 71st: A regiment of the Imperial Guard. Soldiers, but not as specialized as the Templars.
The Mechs: They have a name I always forget. They're worshipped as gods. One pilot lives inside the mech basically, and then has two "handlers." Also "lives" is a bit of an exaggeration. Their torsos and arms are cut and replaced with links to the mech, and their eyes are sutured shut so they can only see through their connection with their mech.
Main characters: Princeps Arlo Luth (mech leader)
Eldar: These aliens that have some vendetta against the cast.
Okay first off I just have to get the ridiculous stuff out of the way. Here it is, in unorganized bullet points:
The term "flesh voice" for IRL human voice. I had to laugh. Upon more consideration, though, I'm not sure what else I would term it...
This line: "He didn't even know why the sight of Ismael reduced to a lobotomized cyborg slave should upset him so deeply."
The dynamic of the god-mechs. Listen. They're GOD-MECHS. People worship them! They can level cities with their weapons!
This is how Princeps Arlo Luth is introduced: "The deck priests were his support crew and his worshippers, devotees come to welcome a living embodiment of their god... Luth knew from bitter experience how easy it was to forget that these scurrying creatures could hurt him...The embarkation deck was a titanic space, as befitted the god-machines of Legio Sirius, honoured engines...."
Pages of this buildup, framing them as super-powerful, nigh-omnipotent creatures.
And then.
"Behind him walked the rest of his pack..."
Oh no.
Can it be?
Luth felt [the other mech's] approach....a declaration of its desire to lead the pack. Luth twisted in his suspension tank, baring his engine's teeth and raising its hackles.
Luth speaks: "When the pack hunts, a strong alpha is its heart and soul...I am still stronger than Moonsorrow and he knows it."
That's right. The god-mechs are an A/B/O polycule.
The author's tendency to compare a new object to an unfamiliar in-universe object. This happened several times, and always went something like "The synth-biotic haptic drive was about as intelligent as a forge world Squeasel, but twice as fast." Sometimes there was already enough context to understand what the object was, which rendered the comparison even more useless.
There was a surprising amount of lubrication, always played straight.....for example, "His exposed flesh was wet with chemical unguents and hot oil lubricants." Sexy!
Next: the good stuff. I don't think anyone is expecting peak literature from a franchised novel, but Priests of Mars had some bits I genuinely enjoyed. I'm not going to spend too much time on "bad" aspects (besides the ridiculous ones), because they're somewhat taken for granted, but I was surprised to have liked as much as I did.
Most of this is stuff that I personally liked, but in the last section I dive into a bigger "craft" decision and what I think made it work.
Language
I believe this is common to the whole 40k universe and not just Priests of Mars, but I love mashups of English words to make new phrases that look familiar enough a new reader can glean their connotations without having to first learn the context of the world. This can also be achieved by using uncommon English words in specific ways. Stuff like Omnissiah, Reclusiarch, Princeps, even Noosphere. I think "flesh voice" was an attempt at this that failed just because of the relative abundance of the word "flesh" in the English language, and that it's been tarnished by overusage in edgier media. Caves of Qud and Homestuck are also good at this, if you're a fan and are looking for more.
Machine Spirits
Haha the Adeptus Mechanicus have a real deus ex machina situation going on here, don't they?!?! Basically, each mechanical object in this world has a spirit that can be supplicated by hymns, binary chants, etcetera. People will make the "sign of the cog" in danger. I thought the computerized Catholicism aesthetic was great and literature needs more of it. The distinction the Mechanicus make between "spirits of machines" (good) and "sentient machines" (heretical) was a little fuzzy to me as a first-time reader, but I was willing to go along with it.
Stuff past this has spoilers, so if you want to avoid them read the book first.
Galatea
I love Galatea. A tank-sized sentient AI who offers wandering tech-priests knowledge beyond imagining by joining it in blissful union? Come on. Perfect.
Scale (the last section...for now!)
Priests of Mars starts out with a HUGE cast of the brightest minds in the Imperium-- Commander Lexell Kotov on his ship Speranza that's half the size of a planet, assisted by a whole bunch of tech-priests and tech-mages to assist him in its daily workings, the Black Templars, the Cadian regiment, and the god-mechs, not to mention the Speranza itself. And it's just one ship in a whole fleet! When you've got all this firepower on your side, it's difficult to establish stakes, or make the reader actually concerned for the fate of the protagonists. But I gotta admit, by the end, I had begun to feel it.
The first way stakes are established is by using the characters' power against them. The first major issue the fleet runs into is when a god-mech pilot has a nightmare/flashback inside of his mech. He believes he's reliving a previous battle, and fires a plasma weapon while docked in the ship. This causes a bunch of damage and casualties inside of the ship--priceless navigation equipment is destroyed, and whole groups of workers are deemed to be necessary sacrifices in order to stop the spread of plasma. Before they even reach the Halo Scar, the Speranza is already gravely wounded, which sets the tone that anything can be hurt, and the fleet hasn't yet accomplished anything they've set out to do.
The most powerful characters also tend to be isolated or overwhelmed in battle. This one's pretty simple. The Reclusiarch of the Black Templars might best any human in hand-to-hand combat, but he's no match for a horde of mechanically-augmented orks or a lava-bodied demon-god from another dimension...
...And that's the third way to up the stakes! Even your superpowerful protags can be wounded or die IF THEIR ENEMIES ARE EVEN MORE POWERFUL. No single human warrior can reasonably expect to beat a literal fire god, and the wisdom of a few-thousand-year-old archmagos is nothing compared to a four-thousand-year-old sentient AI that's absorbed the brains & intelligences of countless other archmagi. Sure, this makes the fights a little wacky, but in a fun way that manages to keep the narrative "realistic" amidst an incredibly unrealistic setting. Because the most powerful characters are faced with obstacles that constantly overwhelm and one-up them, they seem more like people instead of the cardboard cutouts that litter the ground of SFF.
Ending note: the setting also functions as "superpowerful enemy," as all of the characters must stay inside their ships or die, and the terrain of the Halo Scar just ups the ante.
One More Thing
Okay I lied--I have a little bit more. I've been thinking a lot about resource management. It's a game mechanic we all know and love, but limited or depleting resources are a great way to create tension in fiction. The setting already implies a little bit of this, because everyone's in metal boxes hurtling through the instakill environment of outer space and are limited to the supplies of water/oxygen that fits on board. Once the setting becomes damaged (plasma cannon in the Speranza) or restricted (communications cut off as the party boarded Galatea's station / exits cut off by servitors) the finitude of resources becomes even more glaring. If "resource" is interpreted super loosely (even looser than I have already! Up those stakes!), it can also be adjacent to my conversation about stakes--the death of Reclusiarch Kul Gilad, for example, costs the fleet a skilled warrior and the Templars their leader.
Anyway, I don't think there was a lot of "resource management" (as it's strictly defined) in the novel, but I think it can be kind of a useful concept, either by itself, or interpreted somewhat more abstractly when you're thinking about how to add tension to a piece.