So, can Librarians learn to play Astropath? There aren't a lot of Space Marines, and they are expected to go all over the galaxy; even the Deathwatch in this game are expected to cover vast distances, even if only in the Reach, and technological communication has its limits. Can a powerful Librarian transmit astropathic/long-range messages, or are they just sent off, and everyone else has to just hope, assuming that Space Marines will be fine? I don't imagine "regular" Astropaths going out into hell with a Kill Team, but they might need to relay something very important. Even the Imperial Guard, often seen as inferior to the Space Marines in most respects, and known for sitting on the same field of battle for generations, drag Astropaths along for the ride, when nothing is likely to change for ages. How do Astartes keep in contact, if they can't play Astropath?

I don't know the canon stance about that, but I've read at least one case where, in the novel Legion of the Damned, an Epistolary sent out lots of messages through the Warp asking for reinforcements. He also received a message earlier in the novel from his Chapter Master's men. I'm sure space marines also have regular astropaths since Librarians have lots of other duties to fulfill, but it seems that yes, they can also communicate over space.

I may be remembering this wrong, and I don't have the rulebook handy, but doesn't one of the basic Telepathy powers grant the ability to communicate over interstellar distances?

Astrotelepathy, Core Rulebook, p.190. Range is based on Psy Rating: 1-3 - same system, 4-6 - sub-sector, 7-9 - sector, 10+ - adjacent sectors.

Hoorah!!! The me now feels stupid I ask a question, and the answer is right in the main book. Sorry. I remembered it being in the RT book, and nowhere else, so oops. Does tend to make one wonder why Astropaths need Soul-Binding, when I doubt that the Libraria of the Astartes "waste" their precious battle-assets on the withering power of their Emperor. Oh well, still good to know that they do have the option. Thank you for pointing it out to me.

Because astropaths aren't capable of protecting themselves from predatory warp entities.

Essentially, psykers that the black ships pick up fall into four categories:

Psychic Strength__________Strong______________________________Weak

Ability to

protect self

from daemons

Strong________________Inquisitors, Primaris__________Guard Wyrdvanes, Sanctionates

Weak___________________Astropaths_______________________Astronomican, Golden Throne

Essentially, if you're psychically strong, the Imperium has a use for you - astropaths are people psychically strong enough to be useful (and hence at meaningful risk of spontaneous daemonic possession) but without the strength of mind to protect themselves.

If they had the will to shield themselves, they'd not be soulbound because the psykana doesn't wish to waste the rare high-level psykers on an experience which will cripple them.

If they didn't have the power, they'd not be worth the effort of an imperial soul-binding and they'd be lunch for the Emperor.

Marine Librarians never have this issue because anyone capable of passing the recruitment trials of an astartes chapter almost by definition has willpower strong enough to wrap an iron bar around.

Hoorah!!! The me now feels stupid I ask a question, and the answer is right in the main book. Sorry. I remembered it being in the RT book, and nowhere else, so oops. Does tend to make one wonder why Astropaths need Soul-Binding, when I doubt that the Libraria of the Astartes "waste" their precious battle-assets on the withering power of their Emperor. Oh well, still good to know that they do have the option. Thank you for pointing it out to me.

Astropaths are actually the weakest psykers that still pass The Assignment and become Sanctioned. The Soulbinding process is meant to shield them from the horrors of the Warp, allowing them to peer into the warp and protect themselves while sending messages straight into the warp, or receiving messages from there, without daemons and their whispers piggybacking on the carrier wave.

Most other sanctions don't need this, because they aren't so weak as to be used as glorified telefaxes, and so they don't need the additional protection that is necessary to send messages that way.

Librarians, however, represent a group of psykers that are quite strong, both in body and spirit, and are specially selected to become part of the Adeptus Astartes. They go through a largely different sanctioning and training process, that likely takes decades. As such, they can perform the duties of astropaths without having to be Soulbound first.