okay this is proberaly a simple question.

Do halo devices work on untouchables. as we know they diont work on psykers and "the like" and possessed charecters so im curious on Untouchables.

thx

I don't recall offhand any indication that Halo Devices use the Warp to function, so sure they should work.

Personally, just to highlight how changing a halo device is though, I would cause the untouchable character to lose the untouchable quality after hitting phase 1 with a halo device. Just to see the look on their face. Of course don't tell them this right away either, just have them get hit by a psychic attack at some point.

Now, I'm a bit rusty on this, but in the RT stuff, isn't it clarified that the Yu'Vath (or however its spelled) created halo devices? Are they not particularly capable of manipulating the warp in some odd way? I would be surprised if it wasn't some aspect of warp taint. But once again, as it is also a physical device, i would have it affect untouchables.

Untouchables are, I think I've read, technically a form of psyker. I'm not sure where I read that, but I seem to recall it. Maybe in the Horus Heresy novel Nemesis ?

If that is the case wouldn't that put them in the "Can't use Halo devices" column?

Personaly I would say no. The Halo devices are party physical so in some ways they could probably affect untouchables, but considering that they (from what I read in RT) seem to draw heavily from the warp I am guessing they would find it very unpleasant to be around untouchables, much like a psycher would.

So it boils down to the following question you have to answer yourself (unless it get´s some official clearance in the futur, which is highly unlikely).

Is the change of the Hallow Device brought about by the powers of the warp or not?
If you answer to this is yes, the answer to the topic is no.
And the other way around.

there are a number of things to consider here and firstly some clarifications to make:

1. "Halo Device" or "Halo Artefact" is not a specific thing but a description used to identify a number of objects found in the halo stars.

A. firstly there are the ones created by the Yu'vath of which the only kind we know of is the Psycharus Worm which is deeply linked with the warp (these would not even work near untouchables and cannot bond with them either) these does not bond with people marely "attaching" themselves to psykers or navigators to draw power.

B. secondly there are the more iconic ones that are descriped in DotDG, these devices are not created by the Yu'vath, in fact the race that created them are unknown and possibly extinct. these devices does not seem to draw on the warp for any reason, in fact going as far as be unable (or more precisely unwilling) to bond with individuals who do.

2. the matter of Psykers and Untouchables

A. Psykers is a more or less natural orccuring phnomenon created by the Old Ones as a active (if sometimes unconcious) ability to draw on the power of the warp, this is, if not common, then known in nearly all races to some degree.

B. Untouchables are not just another kind of psyker, the individuals that are born as Untouchables carry the ultra-rare Pariah Gene that was planted in the human genepool by the C'tans at the end of the War in Heaven. They were created as the crop of the weapons the Necrons use against psykers. Unlike psykers who can actively use their powers, the effects of the pariah gene are only passive, though some such as the assassins of the Culexus Temple have learned to strenghten the effects to the point where they kill psykers simply by physically touching them.

the novel Nemesis feature (amongst others) an Culexus assassin (which now are chosen from the bearers of the Pariah Gene) called Iota however she is not a true Untouchable as she is a clone, artificially created to an effect that mirror that of an untouchable, likely as a psykers whose powers work "backwards", but true untouchables are impossible to artificially create, they are born not made.

3. it is not so much what a Halo Device can do but what it chosses to do. Halo Devices are in atleast some ways sentient and it "will accept no influence but itself" as such it does not bond with people possessing a Dark Pact or psykers or the like.

so the bottomline is more likely whether you judge the Pariah Gene to be an "influence" which psychic powers apparently is, personally I would judge that the Device would not bond with an Untouchable as the Pariah Gene is directlty created by the C'tans which is not only the most ancient beings of all times but also the singly most powerful beings in the material realm, possibly even beyond that, their name literally means "star gods".