So, I miss these heinous monsters from 3rd ed 40K. I'll be the first to admit that, in the game, they weren't always the most useful unit, with no Get Back Up, and a bit of a cost, but they were cool, they COULD work, and they were a model I rather liked.

I'm working on a small, secondary-seeming Necron Dynasty, led by one Phaeron Akhenatekh. This is the slumbering dynasty that my RT character, Korvallus, stumbled upon about a century ago, and picked up his weird cargo. In addition to her, this dynasty is focusing on creating Pariahs. In not-standard fashion, the Necrons have taken people captive, and are trying to breed them in intensified chronofields, trying to form a more frequent occurrence of the Pariah gene; where they got the initial source is anyone's guess, whether they captured a Culexis Assassin, or have always had it, but they want to make a stock of Blanks, if you will, to convert into Pariah Necrons.

So, the point here is, were you to decide to tackle using Pariahs in THIS game generation, where they might not still exist, but they could be a project of a single Dynasty, maybe, would you favor taking say, an Immortal stat block, and adding the Null template to it, or build a potent Blank warrior, like a Culexis, and add Necron bits to it, giving it the Machine trait, and deny it the other Necron advantages (this is more what the TT game did). Either is possible now that their fluff is in limbo, but what seems better? Thanks.

The pariah as a concept will still likely exist, you cannot simply remove them from existence and retcon them out (even if you're Matt "Cheese" Ward).

I can't think what's in the book off top of head but Immortal statline is probably a good basis, add untouchable and immunity from psychic powers (perhaps use the Abhor the Witch but always active?) Machine (8) as opposed to actual armour points would keep them as potent enemies. As mentioned yep, they don't get reanimation protocols or the normal benefits but will still phase out when beaten of course.

One thing to remember, these guys had Warscythes which as the fluff said could cut a hole in a bunker or slice the barrel off a Leman Russ. So a big nasty unwieldy two hander with power field, silly high Strength and Pen etc. So overall I'd say its better to start with a Necron base and add/remove relevant traits rather than take a blank and make it into a cron.

It depends what you see the Pariah as. If they've got organic bits in them, they shouldn't have regeneration.

The warscythe is already statted - although if I recall theirs had a built-in gauss blaster. Statline wise I'd take an immortal, add in a warscythe for close combat, and remove regenenration.

Soulless is a more significant thing. Untouchables are one thing, but a pariah is high (low?) level one, like the omega-minus encountered in Atlas Infernal, who are not only virtually untouchable to psykers but damp psykers and even mortal courage in a localised area.

I would suggest something akin to the Abhor the Witch rule, but in addition, give them daemonic presence. They're not daemons, and won't be vulnerable to things designed to affect daemons, but the area WP penalty accuratly captures their aura of terrifyingness and the damping effect on nearby psykers.

I thought that Pariahs...much like a Theoretical first sequel to the Starship Troopers movie....never existed, that all memories of them are a mass delusion

Thinking Navis Primer's Untouchable (X [maxxed]), Fear, From Beyond, anda variant of the Tyranid Shadow in the Warp, o drain the efforts out of the psyker's work should sum it up well. Might go for a mish mash of the Immortal's stat block, coupled with the Culexis from NP; figure nothing in that book should be so scary to Space marines, so the Necron bits from OReaches will make it cool. Might post it, once done.

Warscythes with in-build Gauss Blaster.

Man I hated those weapons in TT. In fact I hated any kind of Necron army, Gauss weapons inflicting Glancing hits on roll of 6.

"PURGE THE VILE XENOS"