So I was thinking that since my main villain is quite weak physically but super high in the intelligence department and piloting what is for all purposes a floating laboratory masquerading as a hospital ship where he performs all sort of horrific experiments to extend life that I wanted to have him be able to present a unique and quiet possibly very deadly challenge to my player's health. ( aside from the hoards a screaming "cured" patients and virus grenade equipped hit and run parties). I was thinking of resurrecting an idea that involved turning a squad of space marines into combat servitors. for the most part they would still be in there armor and be programed to use the weapons that they come equipped with.

I was trying to come up with some stats or ideas how they would act, I don't just want servitors in power armor, but something that comes off as truly terrifying and that only gets more worrisome after the helmet comes off.

As for were the poor marines come from I was thinking a squad from a fleet based chapter or even a deathwatch squad that somehow ended up in the expanse.

so any ideas how these guy would come across? How would you build them if you were going too?

Oh and no, I'm not letting the party keep any if they get to the point they have to fight them.

There are some experiments which even the mighty Adeptus Astartes find so abhorrent that they banish the mere mention of them to the deepest crypt vaults and data tombs of their most impenetrable fortresses.

In some cases, few outsiders would understand their hesitation: for what difference is there between a creature such as that, and one of the proud Dreadnoughts that stride battlefields in the Emperor’s service? The Adeptus Astartes know, as do the Techmarines that perform the procedures, and the Magos Biologis that discovered the technique.

Animated Servo-Astartes

More than two meters tall, clad in ghost-black power armor, and clanking with the weight of age and implants, these are hardly true Space Marines anymore. They are implacable, striding ever forward without running, without flinching, and without dropping even after hits that would fell an Astartes warrior.

Captain Yonsun did not know what was in store for him when he accepted his Chapter Master’s orders to take a Strike Cruiser of the Shimmering Dragons chapter, and his Third Company to the Achilus Crusade. Yonsun would lead with the initial reconnaissance sorties into the Crusade zone, and crush any potential staging grounds he found.

The crusade started badly, as the Shimmering Dragons were blown off course on the way to the initial mustering system and into the Koronus Expanse. The Strike Cruiser’s Navigators initially believed they could return quickly to the Maw and take their place in the warhost. Instead, they were caught a second time in a cluster of darker warp storms, locking them in a lonely system in the Koronus Expanse for almost a century.

The system had no inhabitable planets, and the Strike Cruiser did not have the supplies to maintain itself for such a long stretch on its own.

While the Shimmering Dragons maintained their composure for the first decade, conserving supplies and practicing ritual hibernation, it soon became clear that no help or relief would arrive. With their enhanced metabolisms, the Astartes warriors were forced to trust in their stoic resolve as supplies ran dangerously thin. When it became clear that even cannibalism of their serfs could not sustain them, the company faced a harsh choice.

At first, Captain Yonsun and his senior staff placed themselves into deep hibernation and stasis to preserve more resources. Then, the Strike Cruiser began shutting off all but the most critical systems. As the warp storms outside the ship grew stronger, insanity and chaos cults sprang forth from the crew. The battle brothers still awake were driven back by revolts among their former serfs and servants. Warriors left awake crushed cult after cult as chaos worship spread across the ship like a vile miasma.

This sapped the Shimmering Dragons’ strength further, until only a core of hardened brothers still guarded the hibernating brothers in the deepest bastion of the ship.

Finally, after another decade of struggle against the encroaching Chaos, there was little left for the active brothers to do but permanently seal their senior staff in the final bastion and completely cleanse the Strike Cruiser of all life.

The senior staff of the Shimmering Dragons’ Third Company awoke after a century of chaos-fueled hibernation dreams. The Strike Cruiser’s spirit had finally determined that the warp storms had faded, but this did not comfort what few were left.

The Strike Cruiser was a ghost ship now. What few serfs remained in huddled corners were maddened chaos spawn, and the Senior Staff had only survived thanks to the sacrifice of their brothers. Astartes warriors lay dead in every hall of the central monastery: either from wounds or from a final lack of nourishment required to keep living. They had died so that their senior staff might continue.

It crushed Captain Yonsun’s spirit instead.

What the Company Captain, his two senior Sergeants, their Techmarine, and the Senior Apothecary lost that day was not just their brothers, but also their sanity. But they would not let that sap their vengeance or their dedication to fight Chaos.

The Shimmering Dragons were sons of Ferrus Manus, bearers of Iron Hands geneseed, and Yonsun’s last Techmarine understood enough ancient lore to bring back what he could of his brothers. By replacing their weak flesh with stronger machines, the Techmarine built a new army for his Captain.

When a Rogue Trader wandered into the system, the remnants of the Shimmering Dragons saw their chance. They boarded the ship under the pretenses of parlay and killed everyone they found, Captain Yonsun now used his now-Implacable brothers in the only role they could still fill. The Captain stole the ship’s Navigator, and had him wired permanently into the Strike Cruiser.

The Shimmering Dragons would give back the grief they had received from the Koronus Expanse, one ship at a time.

Yonsun’s Servo-Astartes are baleful creatures that barely acknowledge the existence of other creatures. They look simply so that they may kill whatever targets they see, and stride forward in perfect form. With heavy bootprints, they know no tactics except what Captain Yonsun or his officers give them, but they can track and kill anything in their path.

Only in close combat does the talent of Yonsun’s Techmarine become obvious. For there, the Servo-Astartes suddenly come alive, predicting and efficiently ending the life of any unfortunate who thought that these implacable beasts would be easy to fight in grappling range. When their foe is dead, the Servo-Astartes slowly draws himself back up to full height, then again begins implacably moving forward to continue his final orders.

Structure

While Captain Yonsun is in overall command, his two Sergeants each control a ‘squad’ of ten Servo-Astartes. The Apothecary has learned how to repair these brothers of iron, and often follows the Company Techmarine on raids against whoever he finds. Mad with need, the Apothecary now looks for subjects to test out new augmentations on, whether the experiment will be pleasant or not.

The Techmarine has a goal of his own: discovering some way to return souls to the brothers he has lost to please Captain Yonsun.

Stats

In addition to ‘typical’ Space Marines (lvl1 Deathwatch Characters?), add in The Flesh is Weak 3, and Implacable (no fear, will never retreat, will never run).

Armed with Bolters, Melta Guns, Heavy Bolters, Missile Launchers, and Plasma Guns (all Best Craftsmanship).

Tactics

The Shimmering Dragons prey upon whoever they come across. They require supplies, materials to craft more weapons, and information about where to find their next target. It doesn’t matter if they find an Imperial ship, a Xenos ship, or a Heretic, they will act the same.

As befits a Space Marine Company, they strike out with a small number of Thunderhawks or drop pods, do whatever damage is necessary, then withdraw as if they were never there in the first place.

I don't know how well the power level transfers over, but isn't there an entire section of Dark Heresy's Creatures Anathema devoted to the products of Tech-Heresy?