"They do not fully understand what death is and this makes them dangerous to be around. In the culture of the Heralds, each being is made of many kinds of interacting life. They live and die in a cacophony of birth and death, fading and renewing all the time. They are a colony of things. They assume that everybody is.
"If someone dies around a Herald, they will keep speaking, addressing the microfauna consuming the corpse from within. If not prevented or advised otherwise, the Herald will 'garden' all the forms of life upon the corpse into a coherent whole, inhabiting the old form. It is the polite thing to do. Like helping someone who falls sick at your home, or offering new clothes to someone who has spilt their soup. They will educate this colony of things in how to consume the remaining chemical memories of its former host, how to walk in its body, then politely let it go. This may take time...
"Though the Heralds are by no means evil things, they are so alien and strange that to most people they may as well be. They prefer to deal with intelligent undead, or other very long-lived and indifferent individuals. Unprejudiced. The surface as a whole is strange to them. They value calm, politeness, and a discreet hand. You can never be sure how someone will react..."
-Trench Heralds, from "Fire on the Velvet Horizon"
I hadn't heard of this book, but I'm entirely unsurprised to see that this is the same duo that made Veins of the Earth. The monsters in that book are so, so delightfully fucked up and this has that same energy. Have to add this one to my wishlist.
Get you “Fire on the Velvet Horizon” and “Return of the Lazy Dungeon Master” and you’ll be ready to run some awesome games. Maybe get the PHB if you have some money left over and want to know the rules or w/e. Skip the DMG, it is literally 100% worthless.
FotVH is full to the brim with people who made bargains or wanted something to turn out some way who wound up in a state of horrible regret because of how things turned out
So yeah in other words go for it. Warning though, they will probably want to be paid in diseased spines