So, I was wondering if anything I am about to say seems particularly off, or unfeasible:

A party is traveling through space, above a seeming frozen wasteland. Unexpectedly, they are surprised by being fired upon from the ground as, unknown to them, a Necron Gauss Pylon has materialized on mountaintop below them. Acquiring a firing solution, it rakes the crew's vessel with a branching jolt of green energy. I feel the weapon could fire like a lance, thus allowing it's gauss property to "penetrate" the armor, and then it could hit multiple times, like Eldar pulsars do, maybe up to six times, or rolling till it misses; this would represent numerous branches slamming into various areas of the ship simultaneously. This should, like a well-rolled Pulsar volley, leave the explorer's ship very injured.

Upon running away, and not detecting pursuit, the crew might think that they have gotten away alive, several systems burning, but alive. What they don't know is that one beam, slightly different than the others, was a "Boarding Action" attack, and their ship has been infiltrated. The tomb, not up to full operation, simply beamed a small? group of Flayed Ones aboard, to finish them off. If they win the fight, the Flayed Ones disappear, returning to the tomb structure, and if they fail, the Necrons disable the ship, till "bigger" assets can be mobilized.

Does any of this seem odd, impossible, or whatever?

As an aside, how do Necrons traverse deep space? I've seen them literally bend time and space, strange since the place that does that is anathema to Necrons, but I doubt that their ships can do that, or they'd be everywhere. Are they just slow, or can they "matter-jump" distances, and cover space ground quickly?

In the latest fluff, the Newcrons now use " Dolmen Gates " instead of a more Star Trek-y warp drive.

I think this is possible, though utterly ruthless. Lance strikes are going to hurt and kill a lot. They do have non-warp teleportation too, so that works.

I wasn't familiar with Dolmen Gates, which is a neat addition to Necron Lore. A little upsetting that they would need this because the Necrons had gone to war with the Old Ones prior to discovering the C'Tan, so presumably they must have had some FTL capabilities at one point.

My only problem with the scenario is that it's unlikely to kill everyone, so I'm conflicted as to if the Necrons would try it or not. The canonical year for Rogue Trader is before the first recorded sighting of the Necrons, so I've been hesitant to use them in my game because of it. It could be a Dynasty attempting to sample what the effective resistance of Xenos race are, but then they wouldn't be broadcasting their position quite so blatantly with the Pylon.

I'd switch the order of the encounter and try and make it more like the Borg's first appearance in Star Trek except grimdarker. Have your PCs encounter a planet with a recently destroyed Xenos civilization, either one you've created or perhaps a Rak'Gol outpost. Assuming they go down to investigate, have the Necrons board their ship at this point, kill a few crew members and attempt to access, or possibly even trying to destroy the PC's vessel. When your crew come back, if the Flayed Ones appear to be losing, have the Pylon appear to take its shot, and the Flayed Ones extract during that time.

Assuming this all works as planned, the Necrons gain valuable intelligence on the Imperium, and your PCs may be left wondering what happened. A good seed for a potential Necron adventure, or just a standalone reminder that there are terrifying things that come up during an exploration.

Yeah, that was probably the one 'cron change I didn't like... I ret-croned the ones in my game to use Stargate like technology. Which is to say, direct portal-to-portal wormholes while their ships use some kind of hyperdimensional FTL drive. Which I take to be similar to the Tau warp drive, but way, way more precise and capable. Of course, part of this is because I like Stargate, and we are talking about space egyptians with god complexes. Anyway, they do use portals for boarding actions, so that part's perfectly viable, and they'll phase out when dead.

I personally would describe it as a battery of Pylons scattered across the surface of the area, and fire them as such. I would also treat them as a combination of a Macrocannon battery and a Lance (say gaining "Lance" in a damage roll of 10) and roll them as such. Also, give them an extra-nasty critical. Say roll twice on the chart, or just give them a 2 DoS critical. The idea is to try and cause a lot of damage that will need to be repaired without doing so much crew and hull damage as to render the ship inoperable. Also allows you to adapt the deadliness on the fly by having some of the battery "loose LoS behind mountains"

As for the 'boarding force' I'd use standard Necron Warriors, perhaps with some spyder support. To quote wiki:

"Made up of a small number of Necron Warriors and Scarabs, the Raider forces emerge into the outside environment with complete autonomy to carry out their mission as they see fit within the limits of their programming. The Raiders' purpose is to scout the surface of the Tomb World and any nearby star systems, seeking data on the location and status of the galaxy's other intelligent races."

While Flayed ones:

" pecialised close combat troops who appear from an unknown pocket dimension of their hideous kind to join the Necron armies in battle, though never by invitation from the Necrons themselves. "

I like the basic idea though, and may steal it for use in my own game at some point. Era is right though, the Necron need to have some motivation to fire. Which generally means some reason why they believe their tomb is about to be found out.

It's also noted that small groups of necron may have appeared well prior to the official "first sighting" but were in small groups and not properly identified.

I don't see any problems with the scenario. I'm with Marwynn in that it seems a bit ruthless. I'd let the party get some inclination of trouble and if they pursued it that's their fault. Also, I probably wouldn't go with ground-to-space weapons unless the party came down to low orbit. I'm not too keen on the Flayed Ones, either, though I'm not up on the latest ret-cons. I know if I used them, they'd all be wearing RDAnderson's skin (poke at Stargate there, Quick). I'm with Erathia, in that you need a motive for the Necrons above "they's traspassin' on our land." If they aren't going to kill everyone, then why would they expose themselves to massive retaliations?

Yeah, that was probably the one 'cron change I didn't like... I ret-croned the ones in my game to use Stargate like technology. Which is to say, direct portal-to-portal wormholes while their ships use some kind of hyperdimensional FTL drive. Which I take to be similar to the Tau warp drive, but way, way more precise and capable. Of course, part of this is because I like Stargate, and we are talking about space egyptians with god complexes. Anyway, they do use portals for boarding actions, so that part's perfectly viable, and they'll phase out when dead.

In my interpretation, I've changed the "dolmen gate travel network" to be something more like slipspace from the Andromeda tv series, and that's for really long range travel, while they still have their inertialess drive for short to intermediate range FTL needs, but a single jump, while extremely fast, is range-limited because you can only go so far in a straight without running into something/running into gravitic/spatial anomalies to disrupt your inertialess drive field, which when going FTL is bad.

Alternatively, run it something like FTL in Mass Effect and Dolmen Gates are like the Relays.

I liked things back before "everybody uses the Warp for FTL", and in that setting the Tau used something like the Alcubierry(sp?) warp drive.

Part of it is that I sort of miss Oldcrons, and I know them much better than I do Newcrons, so I might've had the higher functions of the tomb be off kilter, or maybe totally fried, and so the lower systems are acting on a more incomplete, possibly unintelligent set of instructions; a computer must follow orders, even dumb ones, without an intelligence, organic or artificial to oversight it, and note the error. While I suppose even Warriors and Flayed Ones must have SOME intelligence, I like to think of them as a bit like Gaunts, drones dependent on the Hive Mind to be totally efficient. I liked the ideas of Flayed Ones because I forget their new fluff, and liked the combination terror tactics/possible stealth tactics, plus their melee combat might give the players a bit more chance, while their lack of Gauss weapons spares the party, and NPC crew from that sort of cheese, first time out.

If the players were flying under my NPC RT, he could even give them info as **** went down, because his Jericho mission most of a century before encountered a small tomb, and it quickly fragged the Hammerfall , sending it back to the Expanse for good, and causing the swap out of the Nova cannon for torps. While Korvallus didn't stay to study his would-be killers, he knows a little more than some, like how quickly they can wreck a cruiser, and their boarding actions policy. Not actively running anything, at the moment, so no one has to anticipate this in the near future, but it can be fun to iron bits out, for just in case.

The nice change about the Newcron update is that it does allow for the existence of the Oldcron fluff. Their interpretation is now pretty much what you have defined: They have lost their "intact" leaders and react more on instinct than anything else.

I still prefer my Necrons to be unbearably overpowering. Maybe it's a truly damage Tomb World and your players think they're fighting Necrons, when in fact it's a group of Xenos that discovered the Tomb World and have appropriated the weapons and somehow rigged the Pylon to fire at any moving target. If your people know the 40K Lore they can think they're dealing with Necrons, then it turns out nope, just weird Xenotech and the threat has passed.

And then the Tomb World can recover from the sabotage.

>> Of course, part of this is because I like Stargate, and we are talking about space egyptians with god complexes.

I asked you nicely to stop talking like this.

you know how I get when you go on like that.

I once ran a RT game where there was a potential acquisition of a diamond of three Terra masses guarded by a Necron relay station and a tomb world. The RT looted the station, his on board AdMech thinking they were deactivated Men of Iron. Two days later, very awake Necrons arrived in system as the party was salvaging a wrecked exterminatus cannon armed cruiser over the Tomb World.

They began boarding the vessel in assassination strikes. The Lord attacked the plasma drives, teams lead by Phaerons went after the Teleportarium and life support, and 20 warriors were sent to the bridge to gauss out the observation dome. The party had to kill them before the dome was destroyed and everyone was sucked into the void.

Necrons do not screw around, they know the weakest part of the fleshy aggressors is their command structure. Necrons are going to gather data and make the most devastating attack they can.

Now, the crew proudly wears battle trophies of the xenos they slew as they made their retreat from the system. Unbeknownst to them, they are being pursued by the Lord, who wants to reclaim the stolen "bodies" of his underlings.