So, in the long-term campaign I'm running there is an overarching plot of treason within the Calixian Mechanicus, specifically the Disciples of Thule. The gist of it is that those Explorators on Illisk found something that "opened their eyes" and "showed them secrets of the Omnissiah". Now that renegade faction has grown and bolstered its forces with Illisk's resources and manufactoria.

Enough backstory, on to my question to you guys. I created a system within the Foundling Worlds known as Sneron which is home to a burgeoning AdMech controlles promethium and starship fuel refinery installation orbiting a massive brown dwarf.

The Magi in charge of the station have been suffering ongoing pirate attacks and have turned to the Disciples for aid, not knowing of their heresy. This is when the Disciples are to make a big power play and seize the station and its reources.

The Explorers will of course miraculously be present for this, but I was wondering how to go about planning the Explorator attack. My current iteration involves Tech-Assassins ambushing the Magi during a formal meeting with the Explorers while their forces storm the station under the guise of a pirate boarding.

Any other suggestions or ideas?

H-h-hmm... you have Mechanicus Faction A (secretly a renegade group) that is not recognised as such by Faction B.
Faction B is running a space stations "and stuff" that Faction A wants to take over.

Is this "station and stuff" having regular contact with other groups in the Mechanicus? If so, a "Mask of Normality" is a nice thing to keep. For this reason the "renegades" might want to capture the head-honchos of Faction B "rather intact": they need
to salvage their personal codes and turn their bodily components into literaly puppets that can be used the few times a year
said statiosn has contact with anybody official.

In turn, the head-honchos, once aware what is going on, could try to self-destruct both themselves and the station. Perhaps the RT needs to talk them out of it?

Furthermore, an Mechanicus Renegade attack should feature "electronic warfare" to take out subsystems, jam communications and such. The one thing they perhaps cannot block is an Astrophatic message, thereby the first target for assassination will be a present Astropath (if any!).

Also they have brought the Disciples of Thule already in. This means those Mech Assassins well, will know the security codes to open airlocks etc. Lock down and purge O2 from area of the station. And it could be a real pirate attack, after all they could have their operatives already in place. Just need the distraction and of course when they are attacking using info provided "by Disciples of Thule" they can be targeted and easy to destroy. Oh and the player ship(s) should also be targeted by the raiders.

Thanks for the suggestions, E-warfare will defin8tely be a thing and I do enjoy the idea of an actual pirate attack masking the true threat.

I appreciate the food forthought.

Another idea is that since it's Admech against Admech, it could be highly possible that the opposing faction has planted back-door codes / overriding commands in certain systems, weapon defenses, doors, servitors, etc. It would be highly problematic for the PC's if they fought off the attack, only to be in a secure area recuperating when a fellow "friendly" Admech personnel goes to a cogitator console, enters a code in that engages the defense weapons mounted in the walls and the servitors by the doors, and then leaves. Or they are attempting to flee an area flooded with contaminants caused by an unknown saboteur, only to discover that the Admech person in front of them locked the door everyone was attempting to flee to. Ahh, so many options.....

But yes, ECM or EECM warfare is a great start for any tech sophisticated adversary. Having cogitators, servitors, vehicles and other tech savvy gadgets suddenly shut down, go haywire, or refuse to operate ("error..error") would definitely be annoying. And maybe even frightening if it is their shuttle that is heading toward the ground at earth shattering speeds.

Tech Heresy and Mech Assassins.

I'd read up on the Logicians if I were you. I know they specifically have specially created mechanically enhanced bio assassins.

Maybe they are collaborating with the Disciples? Double your heresy for the price of one!

Not contributing anything useful here, but I just laugh a bit to hear some of these answers about AdMech hacking each other, and some of the other hi-tech possibilities, when, in my mind, I know more about computers than so many Tech-Priests do, and the closest I can claim to having "1337 5|<1LL5" is having watched Johnny Mnemonic, a few times. While I wholly admit that some members of the Cult Mechanicus know plenty about their wares, so many only know hwo to do certain things, and only by rote, that it seems funny to imagine them actually doing all of this stuff, if they even see it as okay to treat their precious devices so rudely as to hack into their machine spirits, and screw with their operating procedures. oh well, I know that it could work; I'll just laugh at how I view it wouldn't for so much of my AdMech vision.

Not contributing anything useful here, but I just laugh a bit to hear some of these answers about AdMech hacking each other, and some of the other hi-tech possibilities, when, in my mind, I know more about computers than so many Tech-Priests do, and the closest I can claim to having "1337 5|<1LL5" is having watched Johnny Mnemonic, a few times. While I wholly admit that some members of the Cult Mechanicus know plenty about their wares, so many only know hwo to do certain things, and only by rote, that it seems funny to imagine them actually doing all of this stuff, if they even see it as okay to treat their precious devices so rudely as to hack into their machine spirits, and screw with their operating procedures. oh well, I know that it could work; I'll just laugh at how I view it wouldn't for so much of my AdMech vision.

They actually do it one of the stories, forgot witch book (maybe Priests of Mars?) but one of them organises a secret meeting with another adept and basicallly hacks/mindrapes the other one and even erased his memory of the meeting.

Also this is 40k: in Mechanicum, there was this chaos scrapcode that can change from computer virus to biological virus and back. Que this happening:

Techpriest: "Thank the Omnisiah,w e made it safe in the hermetically sealed bombshelters."

Comunication device: "Driiiiiiiiiiiiiiiiiiiiing!"

Techpriest: "Hallo? Yes we made it safly insiiiiii-oh crap! aaargh! splut."

http://wh40k.lexicanum.com/wiki/Sicarian_Infiltrator

Sicarian infiltrators seem just to be the thing you need. Mechanicum assassins that use electronic warfare to become invisble.

Normal definition of stealth: To not be seen or heard by the enemy.

Admech definition of stealth: If we make the enemy blind and deaf we won't be seen or heard. Brilliant!