Esteemed fellow GMs!

How do you go about your player characters learning new psychic powers? I mean, they just fulfill the prerequisites, pay the XP and immediately may use the newly learned power? Is it something which is just there in the psyker's head and in a tense situation comes to the fore and from that point onward she can employ it? Or does the PC have to read weighty tomes, meditate, and/or consult a mentor between game sessions?

I just ask because usually my players earn enough XP in 1 to 2 sessions to learn a new power and then of course they want to make use of it immediately. But usually we are right in a running investigation or even a fight which started last session and there is no time to go to "HQ" or some save place to read books or talk to other psykers.

Also, are the psychic trees as represented in the core rule book, actually a thing in game? So are the "sanctioned", well-known powers really that well-organized in the WH40K-universe and written down in some kind of AAT-manuals or does a psyker have to somehow "find" a new power by visiting forbidden lore libraries, astropaths or even witches?

I'm all ears.

Spend the xp at the end of the session, get the upgrade for next session. Why should psychic powers be treated differently to any other character upgrade ?

Making a psyker wait a bit longer to get the power doesn't do anything for game balance, because they will still get the power.

Spend the xp at the end of the session, get the upgrade for next session. Why should psychic powers be treated differently to any other character upgrade ?

I did not mean to treat psychic powers differently. I also like to provide some rational for other advances: Tyruss the Confessor was doing a lot of melee combat with his warhammer lately, so a +5 to Strength seems reasonable, because he was working out . Alicia the Assassin spent some nights dissecting corpses with her Inquisitor who happens to be an Ex-Imperial Guards Chirurgeon, so learning basic Medicae is appropriate. The cowardly princeling Harlon turned and ran away in the last three combat encounters, he certainly knows how to take to one's heels, resulting in an advance of his Agility from 35 to 40.

Cutter is a psychic witchhunter formerly from the Black Ships. He can read minds and tamper with memories. Now suddenly his opponents tend to eat the barrels of their guns, because he learned 'Dominate'. Did his psychic mind just evolve on its own or because of a stressful experience? Does he have a tome about telepathy where he learned the right mental training to gain the new power? Where did this new ability come from?

You see what I'm getting at?

Spend the xp at the end of the session, get the upgrade for next session. Why should psychic powers be treated differently to any other character upgrade ?

I did not mean to treat psychic powers differently. I also like to provide some rational for other advances: Tyruss the Confessor was doing a lot of melee combat with his warhammer lately, so a +5 to Strength seems reasonable, because he was working out . Alicia the Assassin spent some nights dissecting corpses with her Inquisitor who happens to be an Ex-Imperial Guards Chirurgeon, so learning basic Medicae is appropriate. The cowardly princeling Harlon turned and ran away in the last three combat encounters, he certainly knows how to take to one's heels, resulting in an advance of his Agility from 35 to 40.

Cutter is a psychic witchhunter formerly from the Black Ships. He can read minds and tamper with memories. Now suddenly his opponents tend to eat the barrels of their guns, because he learned 'Dominate'. Did his psychic mind just evolve on its own or because of a stressful experience? Does he have a tome about telepathy where he learned the right mental training to gain the new power? Where did this new ability come from?

You see what I'm getting at?

On the other hand, a character suddenly gaining Scholastic Lore: Administratum, while in the middle of a Tyranid-infested jungle.

A character gaining Power Weapon Training while they've been investigating a cult of mutants in the dark sewers beneath a Hive.

A character gaining Tech Use while on a Feudal World.

Well, I would not allow that in my campaign.

It can mean different things for different psykers. The correct answer is all of your ideas Eltom. Some say temples of the psykana scholastica train from ancient libraries, others push their psykers on journies of self discovery and inner awakening, really, it depends on the path of the psyker and his own experiences within his scholastica coven to determine the correct course.

Spend the xp at the end of the session, get the upgrade for next session. Why should psychic powers be treated differently to any other character upgrade ?

I did not mean to treat psychic powers differently.

But that it what you are doing. You let players take other advances instantly, but you want to restrict when psychic powers can be taken.

Yes, you could try to make players justify how they learned their upgrades. But that might make them takes months worth of sessions between earning the XP and getting the advance, because the campaign remains in one place for so long.

Spend the xp at the end of the session, get the upgrade for next session. Why should psychic powers be treated differently to any other character upgrade ?

I did not mean to treat psychic powers differently.

But that it what you are doing. You let players take other advances instantly, but you want to restrict when psychic powers can be taken.

Yes, you could try to make players justify how they learned their upgrades. But that might make them takes months worth of sessions between earning the XP and getting the advance, because the campaign remains in one place for so long.

Isn't that a bit of extrapolating? Eltom never discussed the details of how he handles advances in his original post, and after a similar question was asked he responded that he runs an organic approach to acquiring advances, preferring to allow skills and talents to be taken that make a narrative connection to the characters action or waiting for breaks for things that didn't come about naturally via gameplay.

I sorta wonder why your post was mildly aggressive in this regard.

Spend the xp at the end of the session, get the upgrade for next session. Why should psychic powers be treated differently to any other character upgrade ?

I did not mean to treat psychic powers differently.

But that it what you are doing. You let players take other advances instantly, but you want to restrict when psychic powers can be taken.

Yes, you could try to make players justify how they learned their upgrades. But that might make them takes months worth of sessions between earning the XP and getting the advance, because the campaign remains in one place for so long.

Isn't that a bit of extrapolating? Eltom never discussed the details of how he handles advances in his original post, and after a similar question was asked he responded that he runs an organic approach to acquiring advances, preferring to allow skills and talents to be taken that make a narrative connection to the characters action or waiting for breaks for things that didn't come about naturally via gameplay.

I sorta wonder why your post was mildly aggressive in this regard.

Because I've seen that approach before. I've seen players being unable to get the advances they want because the GM doesn't think its justified for them to learn that advance right there. I've seen that go on for months because the plot didn't give any downtime for the training to take place in.

I understand you had some bad experiences from this method, but certainly you can see the folly of venting that frustration out on someone who wasn't related to that experience? Personally I follow a similar method, disallowing Xp expenditures completely until the end of an adventure, with a fewvexceptions when it can be argued by a player to have a narrative justification.

The deal that I've worked out with my psyker player is that the character has to spend a little time experimenting before he can pick up a new power. The character needs to have a few hours to himself and the player needs to expend his use of Warp Lock for that session (including the resultant damage); simulating the fact that his power would inevitably get away from him at some point while he was messing around. I'll sometimes also tack on a minor nuisance side effect of some kind that he has to deal with for a just a little while in game.

@Cogniczar: Thank you for the defence You got may intensions correctly.

@Bilateralrope: Sorry, if you have had bad experiences with an organic approach. In my campaign I really do not forbid any advances to my players. I also do not want to protract getting an advance. I simply want them to come up with some fluffy explanation, why they have their new ability. That's not because I want to restrict advances, only to deepen the playing-experience.