My group had an unfortunate time in the warp. Aside from being lost, slowly starving to death and going insane, they also have around 100 demons nesting inside their plasma drives.

The players want to modify their Gellar fields to contain the area inside the ship, until they can think of a better way of disposing of them. The Explorator in the group is willing to become a HereTek to accomplish this.

I don’t know too much about the lore, but how difficult would such a task be?

I wouldn't say this is heresy, Gellar field size can be adjusted, so you could minimize it down to a more powerful field that doesn't cover the whole ship.

However

This exposes the rest of the ship to the unreality of warp space and its denizens, and could be a genuine challenge to actually achieve depending on PLOT.

This could manifest as something as simple as 'Haunted' or the same penalty from 'wrested from a space hulk' as its been unprotected in the warp.

Or perhaps the core cogitator is infected.

But don't penalize your guys, this sounds like a good plan to me and I would be willing it to work, just using it as a good springboard for later plot hooks.

It really depends Godgolden. I think your running under the assumption they are going to reduce the Geller Field while in warp transit - which would literally translate as a total Player Wipeout! More likely, they are going to attempt this in realspace where the use of the Geller Field isn't required at all - and overall a good plan to contain the daemonic infestation.

[Rogue Trader] is not within my field of expertise, but I would allow players to localize their Gellar Field under the Rule of Cool. Off the top of my head, I believe Gellar Fields are borderline Archeotech? If so, I might start with a Very Hard (-30) Tech-Use Test to be repeated every so often. Option: Base duration is half an hour between each Test. Catastophic failure (3 or more DoF) would disable the shield completely, else each DoF/DoS modifies the time before the next Test by -/+10 minutes.

Within the setting, manipulating the Geller Field to expand to cover other vessels is a routine activity. By all means, any competent Enginseer would be able to -shrink- the field with relatively ease. It shouldn't be a hard action, nor resulting in any chance of catastrophic failure as the range of the Geller Field is not being stressed at all but rather condensed to a much more manageable size than normal operations.

Within the setting, manipulating the Geller Field to expand to cover other vessels is a routine activity. By all means, any competent Enginseer would be able to -shrink- the field with relatively ease. It shouldn't be a hard action, nor resulting in any chance of catastrophic failure as the range of the Geller Field is not being stressed at all but rather condensed to a much more manageable size than normal operations.

Is that right? I would think that the Gellar Field "expects" to be a certain size/strength ratio, such that shrinking the field also weakens it. Please do enlighten me if this is not the case, as I find this matter interesting and will serve me in any future RT-flavoured games I run.

Not sure how canon it is, but in our campaign the ship's main Temple has it's own miniature Gellar field generator.

Assuming your're talking about doing it once you're out of the warp I'd allow it with a tech use check at something like a -10 penalty, meaning it's not a regular occurance but isn't extraordinarily difficult either. It's a good idea for keeping those warp beings bottled up and starving them out once you revert to real space.

If They want to do it while they're in the warp, modifying the Gellar Field emitter to create a second Gellar field inside the first while it's still running , I'd make that much much more difficult. I'd probably require the Shipwright trade skill to do it at -30, or if they don't have the skill it'd sit at -60.

Either way I'd spend a little time figuring out what the effect of having a hundred demons nesting in the plasma engines is going to do to that component... Warp beacon anyone?

Assuming the players exit the warp I'd be okay with this being a possibility. As it has been mentioned a few times in various forum posts and potentially a few times in the rule books the possibility of extending the Gellar Fields to cover another ship exists to enable boarding ghost ships and towing ships through the warp.

That said I believe you cannot have Gellar Fields and Void Shields up at the same time so the ship would be unshielded for the duration.

I'd probably make it a Difficult -10 Tech use test unless the character also had the Forbidden Lore: Archeotech then I'd drop it down to challenging.

Of course you can't go through the warp any more and without Void Shields combat is iffy so it really is just a stop gap until someone is willing to go into the engine room and clear out the demons.

Now if they wanted to overload the Gellar Field and weaken the demon nest I'd allow that too but with a -40 Tech use test (-30 with Forbidden Lore: Archeotech). This would mean the Gellar Field needs to be repaired afterwards but the demons would be substantially weaker.

I had assumed while within the warp

Personally I would let them auto-succeed the test to miniaturize the Gellar field, but slap a time on it that they can modify if they choose to test.

To me this would negate the toughness bonus from being a warp creature but little eels beyond RP.

Well there is that bit about warp creatures requiring some sort of special situation to exist in real space for any length of time. Warp incursions, possessed hosts, summoning by sorcerors. If you just drop to real space and trap them in a gellar field you just have to wait a bit until they can't sustain their presence in realspace any more. That's what I meant by starve them out.

Also I've never heard that you can't have a gellar field and void shield going at the same time. Anyone know about that one?

In the novel Atlas Infernal, a sect of tech-priests is mentioned to have designed Geller Phase-Field scalpels. Hand held units for dissecting the malefic.

Assuming the players exit the warp I'd be okay with this being a possibility. As it has been mentioned a few times in various forum posts and potentially a few times in the rule books the possibility of extending the Gellar Fields to cover another ship exists to enable boarding ghost ships and towing ships through the warp.

As well as the primary modus operendus of the Chartist Fleets and the Trade Fleets of the Imperium!

As for mechanics, I'd recommend Malediction from Disciples of the Dark Gods, Page 118 after using the a Tech-Use test to compress the field over the Daemonic nest. Geller Field is mentioned explicitly in the case-use!

Malediction

Certain antithetical forces and energies, such as a starship’s Gellar Field, a pentagramatic ward, or some sorcerous attacks can have a powerful antithetical effect on creatures wholly or in part comprised of matter drawn from the warp, unravelling and disrupting them on a fundamental level. This destructive effect is called Malediction. An entity suffering Malediction suffers 1d10 Wounds as it occurs and each Round of exposure. Such Damage is not reduced by armour, incorporeality, or Toughness Bonus. Additionally it suffers a –10 to all Characteristic Tests and double the adverse effects of Warp Instability for 2d5 Rounds afterward. Further, having suffered Malediction, a daemon must pass a Difficult (–10) Willpower Test to directly attack or closely approach the source of the Malediction.

Malediction can only affect beings with either the Daemonic or Warp Instability traits.

Good catch!

Also I've never heard that you can't have a gellar field and void shield going at the same time. Anyone know about that one?

It's never flat out stated, but merely eluded to in various books. It's definitely in the fluff, though. There are tons of stories of ships transitioning to/from the warp, and not having shields up. Heck, there are stories of ships not having shields up while at port / Imperial controlled space. For that matter, ships normally don't have their Gellar Fields on unless traveling in the warp, due to the distress it causes the crew. Once again, all fluff stuff, so no RAW. Feel free to play it as you like.

Are there any instances of man-portable gellar field generators in the fluff that would operate like a portable force fields that only affects warp activity? If so it could be a possibility to hobble something together depending on what you are willing to let them do and cost them--maybe a set of extraordinarily difficult tech-use tests and cannibalizing ship/equipment components.

>>>> instances of man-portable gellar field generators

yeah, its called True Faith

Are there any instances of man-portable gellar field generators in the fluff that would operate like a portable force fields that only affects warp activity?

Their are psychic null devices. Protects you from psychic powers, probably some warp stuff too. Only problem is anything physical will hurt you, like a daemon biting your head off. As for man-portable gellar fields, none that I can recall. Not even in any fluff that I've read. However, I don't see why not. If they can make personal force fields which are basically void shields on ships, then why couldn't they have made personal gellar fields? Might be very very VERY hard to come by, as possibly the STC was lost. Their are some fluff examples of gellar fields on a surface complex, which was decent size. Like maybe .5 km x .5 km x .25 km. Not sure how relevant that last example is to you though.

I think the question here is what the Gellar Field actually is, as I'm assuming this is being done in realspace also. In my mind, it's a bubble of realspace inside the warp, meaning summoning daemons inside of the ship is exactly as hard as it would be on the surface of a planet. You're not immune to warp corruption, and daemons don't cease to exist. However while it's up your ship isn't immediately visible to every warp predator out there, and it requires energy, effort and sacrifice to manifest there, and a daemon is forced to accept certain corporeal limitations.

So if you're in realspace, and you still have daemons around, then something has gone terribly terribly wrong. Perhaps there's some sort of warp artifact in your plasma drives that is sustaining the daemons, in which case if you isolate that in the Gellar field you might starve the daemons out. Otherwise if you're in reality and you've got a hundred daemons on board, then I have good news. You're probably already dead, and there's no hope for you.

The good news is you don't have to worry about things getting worse.

If you are in realspace and you have a small army of daemons aboard your ship and for some reason they are being cast into the warp after few hours at worst, there are three possible reasons for that:

-There is an extremely powerful artefact back there, in which case you are royally screwed. You have two options: either go there and destroy said artifact or wait till Eldar/Gray Knights come and do it for you (only problem is they will also kill every human onboard to prevent the chaos taint from spreading)

-There is a powerful ritual going on, in this case there are two possible solutions: go and interrupt it or wait until they run out of fuel to sustain it (and by fuel i mean slaves).

-The GM simply forgot that daemons can't survive for long in realspace, in which case he's either going to call them off after being reminded about that or makes one of the above be the case. (or he simply decides that daemons that can't stay in realspace are lame and decides to keep them around forever, in which case you can pack your toys and leave, since for example a Khorne Bloodletter is powerful enough to kill a 14 000 xp duel-oriented character in a duel. And a Bloodletter is the weakest form of a Khorne daemon... )

I believe the free adventure "Forsaken Bounty" includes messing about with a partially active Gellar field. I'd certainly allow players to try and shrink or enlarge the bubble but take a look at some of the above posts.