So after a few years of being the GM for my group, one of my players has asked to try running an adventure. And so far, he's better at it than me. He allow more freedom, more options, doesn't bog us down with useless information (I like to do that because, not every lead will be real or truthful) and tracks combat better too.

But….he doesn't know 1/4 of what I do about the setting. He starts us off in transit to a location, on a large, warp-capable merchant ship with a crew of 400, and a security force of 5 men, that will take 6 months to reach our destination. (problems already) And it seems at every turn he manages to screw something up.

I don't know what to do here, usually I'm playing god and can tell him "no, a ship that size would have a crew of 10,000's" or "stasis shell is stationary RELATIVE to something, not a point in space, otherwise i could wreck ships and maybe even planets with it" but he's GM and I'm not. Anyone got any advice here?

Also, my character is an Interrogator and he was fine with that, but doesn't seem to understand the kind of authority that comes with it, neither do the other players. For example, i blew out all the windows in a town first time i used a power, now the blunter sticks to me like glue so i can't "wreck the nice things" wherever we go, despite direct orders to bugger off and let me do some magic.

Last thing, I need some opinions about a course of action taken in-campaign. A very powerful psyker burgled my character's mind (the interrogator who know's stuff even the current GM doesn't) [by powerful, i mean psy-rating 14 and WP of 90, might be a demon, he hasn't said yet] and by burgled, i mean copied all my memories, and gave me some of his own back, then fled in the most terrifying way ever. In reponse I sealed the planet, for once they let me use that interrogator authority. My question is, is sealing the planet enough, or would a psyker that strong, who may or may not be friendly towards the imperium (haven't nailed that down yet) with a copy of an interrogator's brain, as well as numerous other known heretics on the planet and a small, unfriendly xenos race, be warrant for Exterminatus?

For your choice, the situation would need Exterminatus, in my opinion. But in the roleplaying game, it is very rare that we just go down to this option, you should be the Interrogator that doesn't use Exterminatus (otherwise, some very complex adventures would just stop at their beginnings).

For your questions as a GM, I live this some times and others; a good friend of me does GM time over time and he's very good, but lacks knowledge on the universe and makes sometimes some decisions that, in my opinion, doesn't fit the universe. My only trick? I tell him his mistakes after the games for him to learn more (the better learnt is the gm, the better will he be for his games, after all) and in play, I accept that he is the GM and, in the worst case scenario, roleplaying games are about imaginary worlds; I change in my head the small details that don't fit.

Try to help him with background info without bogging the game down, like after a session.

Exterminatus is only when there is no apparent way of salvaging a situation, examples would be Daemon Worlds, Worlds lost to Tyranids or Ensalver Infestations that are planet wide.

A strong psyker with some backup? not even worth considering exterminatus. You send assassins perhaps and take him out so he can't destroy the planet, or send the PDF or other armed forces at his Xenos friends.

You have to remember that Exterminatus is final in most cases, you cant use the planet for anything anymore. And the Imperium can't mass produce or terra form planets all the time (not even sure they can at all).

Alexel has the right of it, in my opinion.

For the big setting errors it's best to bring it up after a session, and privately. Most importantly, do not sweat the small stuff. Note: most of the canon that 40k enthusiasts get worked up over is small stuff. If your GM describes the guardsmen from Krieg wearing faded orange trenchcoats, then in this campaign just accept the fact that they have faded orange trenchcoats. If your GM doesn't understand that a stasis field fixed in an absolute position is unworkable then just let it slide and don't exploit his lack of understanding concerning time and space paradoxes.

If your GM insists that the Ultramarines became a traitor chapter during the Horus Heresy, and that they are in fact the dreaded Khorne Berzerkers…feel free to correct that. (politely)

Lastly, Exterminatus = Inquisitorial Failure (in my opinion)

If an Inquisitor did not throw every available resource at reclaiming a habitable planet, a non-renewable resource, from a Heretic then they had best have a damnably good reason for it. Only if the foe is so fearsome that the Inquisitor, with the assistance of other Inquisitors, cannot expel this threat from a planet should an Exterminatus be ordered. Even then the Inquisitor will have to answer for why they couldn't prevent the threat from rising. They would have to work hard to prove they were not negligent. Especially so if they had any previous knowledge of the threat.

The problem is regarding 40K it is hard to define "the setting" as it has changed a lot over the last decades and evolved from one side to the other and backwards again. Read two random and see the discrepancies in them (Enforcer omnibus vs. Eisenhorn omnibus for example). Thus it might be difficult to say one knows much more about the setting than somebody else in my view.

Anyway, an Interogator (beisdes that the term Interrogator is used rather heterogenously throughout the Imperium/Inquisition) has about no power on its own or lets say only as much power as the Inquisitor backing him deems to trust him with. Maybe he was given a Rosette by his patron Inquisitor. But even then, it is not a carte blanche to do everything he wants, let alone command an Exterminatus. An Interrogator should NEVER have the power to use Exterminatus. This is something reserved for powerful Inquisitor Lords and even they do not simply pull it out of their pocket. You need a sufficiently big and adequately equipped warship of the Imperial Navy to enforce an Exterminatus. If there is no Imperial Navy around (most planets never see the Segmentum/Secotr fleets in a thousand years anyway), the Inquisitor in question has to use other measures he has access to.

Have you read Ravenor by chance? He has an Interogator in his retinue, who is sort of a first amongst equals in regard to the others of the retinue. He seldomly commands the others around if at all.

Sealing the planet seems fine and using all of the planets resrouces to locate your enemy makes sense.

I am pretty certain that you need to be an Inquisitor to order Exterminatus and it is an extreme action (complete loss of world, inhabitants and resources). Can you justify that loss to your fellow inquisitors because some bad guy might be on the planet? Is what your character knows really that important?

Think its best to remember the guy is giving you the chance to play the game. I use to GM at a local gamestore when I had free time, and most players I've encountered had no real knowledge of the 40k universe. In that situation, The narrative and theme had to be things they could Identify and relate to when learning how that effected in the game. Truth from Alex. If you feel as a player your GM isnt giving you enough "Fluff", then away from the group give your grievances. When I dont GM, I play in a game that my friend does the most Outrageous things. Example was a DW game where Holy Terra was being attacked by Orcs and we were stationed on Mars for some reason, and we had to stop the invasion. Now, anyone who knows 40k and the outlandishness of the plot, cringes as they read this. However, I still played the game cause he took time to make it, and the overall feel of killing stuff wasnt boring.

Far as IC goes, I agree with Luthor/ID on that. A Interrogator with a Rosette does not have the authority to commit Exterminatus. In game terms, unless your influence is well over 90, I would never even let players come up with the decision of it. Inquistor Kryptman was condemed a heretic for using Exterminatus like it was ordering a burger during the tyranid invasion. A far more reasonable thing would be for your character to begin learning more about this Psyker. Use that influence to set up cells, and determine any signifigance to the Psyker and possible Demon. If so, try to obtain a Grimnoir of Names, and research the TRUE name of the Demon. Influence is a art in DH. Knowing how to play it is really up to the players in the end. Also, depending on your Faction in the Calixus Conclave is (IE. Monodominat, Radical, Xanthian, etc) is how you should be determining your next course of action. Example, if your a puritan, Cleansing rituals and Mind wipe is what I'd be asking for. Radical, Try to see what knowledge the Psyker left me and see how that can be used against him or for my advantage (Aldo this may be what he intended, its all about the mindset of the character)

If it where me, I'd would be establishing my own sects amongst the Calixus Sector without my Inquistor knowledge (As is the nature of the Inquistion at times) and waging a personal war to remove the threat of this psyker, while giving the appearance of the group finding out about this NPC so in turn your manipulating that end to your own. Jesus, I love DH

Thanks for the feedback guys, it's very helpful. 2 things I want to bring up in response.

1: I don't mind bringing up fluff problems after, but the rest of my group know more than the GM too, and they bring stuff up as soon as they see it. His response is usually "this is my planet, eat a weiner." I'm trying to think of a way to keep it all from getting to the GM too much.

2: My character (the interrogator) can't actually declare exterminatus himself, but he is more or less their Inquisitor's right-hand man (and the closest thing to a son the inquisitor has). If he tell the boss-man that a planet has to burn, the boss would likely be onboard with it. We don't use the influence mechanic, as we aren't at ascention levels yet, so it becomes more of a narrative tool at this point.

As for the interrogator starting his own cells, his faction kinda prevents it. The GM is using my framework so the other players can keep their characters, so the Inquisitor is a Radican Ordo Chronos. Publicly, he's Ordo Herecticus. Being a powerful Seer, and being so close to the interrogator, the interrogator can't even drop a deuce without the boss knowing when he'll do it.

(as an aside, at some point I'll tell my players that they get the ****-jobs because their presence causes an explosion of possible futures, so they get sent where anyone else would fail. This manifests mechanically as fate-points)