Can we take a beat here to talk about WH40K's ridiculous Dog Latin? It's an essential part of the line's feel and if terms like Administratum caused me to do a bit of a double-take, I quickly made my peace with it. It's a little silly, but it's a style. Fine.
Until the Officio Assassinorum. . .
I'm sorry, what?!
"What do we call our setting's Office of Assassinations?"
"Why are you bothering me with this? Just grab a couple of suffixes out of the bucket. That's what it's for."
Anyway, the Navis Nobilite. That's like a nobility consisting of ships' navigators. They've got different Houses that have feuds and alliances and duels and all that noble stuff. They persist because WH40K space ships have to go through the psychic realm (charmingly called here The Sea of Souls) in order to travel faster than light. The very specific psychic power that allows a ship to do this and not get hopelessly lost belongs to a fixed number of special lineages who all share the same mysterious genetic mutation - a third eye in the middle of their forehead, that doesn't just reveal the immaterial, but actually functions as a gateway for infernal energies to enter our universe. So much so that if it's opened in the presence of a non-Navigator, there's a very real chance it will melt them down to their bones.
But in the spirit world it lets you steer a spaceship.
Despite its title, this book is only about 1/3 about Navigators. Mostly it's just a dumping ground for all things psychic. We learn here that Orks have psychics, called Weirdboyz, that channel their species notorious Waaagh! energy, but have to carry copper conducting rods because if too much of a charge builds up they, and possibly every ork in the immediate vicinity, will have their heads explode. Because everything about them has to be 200% precious.
Honestly, though, there's very little in this book to complain about (not that I see it as my job to complain or anything). It's got more psychic powers. More equipment. More antagonist templates. More fragmented setting information (I pretty much tripled my knowledge of the Eldar by reading this book, but I still know barely anything about them). For better or worse, it's a typical Rogue Trader book.
I did think the alternate career ranks were a bit better thought out than the ones in Into the Storm. Still probably more of a headache than they're worth, but at least this time each one had an easily-discernible hook that let you gain a talent or power you wouldn't otherwise be able to access. My favorite was the one where you get an alien cybernetic implant that allows you to psychically control technologically reanimated corpses. It's a little odd that you've got to take a level-long detour just to make use of something that is, canonically, an off-the-rack piece of equipment, but if you invest enough into it, the Colchite Servo-Master really is a viable character niche.
The most difficult part of this book for me was the way it centers in on the setting's least appealing thematic tension. Warhammer 40k is a game that wants to have the trappings of horror - one of the things that can go wrong in sending an interstellar telepathic message is that you start vomiting up human hair (excuse me while I get the creepy-shivers forever) - yet it is also a naked power fantasy - the way you're supposed to respond to all these demons is with flame-throwers and chainsaws, and if that doesn't work, your survivors will try it all again tomorrow.
These competing impulses pull the world in two separate directions and as near as I can tell, the rubric for deciding how to resolve these conflicts is "whatever is most pessimistic and authoritarian." So you get a whole long section about how the Imperium's witch-hunting is good, actually, because an undetected psychic can become the weak point in reality that allows demons to invade. Or, to put it in the book's own words, "they risk an entire planet by showing mercy to a single individual."
I sometimes wonder whether these books actually have an unreliable narrator or whether they're just telling the simple objective truth and I'm merely refusing to believe it.
Ukss Contribution - There's actually a lot of cool baroque horror/fantasy here to choose from, but once again I'm going to have to go with something simple. One of the sample familiars is a type of mechanical hawk made from copper and glass that is able to detect psychic energies. I like that image. There's no art, but the thing I'm imagining is a handsome Deco-inspired collector's item.