I sat down and formulated a new Chapter, as one of the Lost Primarchs' descendants. They are weird BS, the Void Shadows. I haven't finished their stuff in any DW rules, but the brokenness starts with them being Nulls. Yes, I know that is broken, but I didn't care at the time. It severely hinders the Space Marine process, but it is rather stable, if the initial changes don't kill the recipient. As a side effect of their change, all Void Shadows are albinos, leaving them with whitish hair, pale skin, and pinkish-red eyes. They are a bit wan and frail-looking, by Space Marine standards, but still robust enough to stand among their brothers. They wear black and red armor, and specialize in stealth and recon. Initially, the Void Shadows were created to travel out beyond the edges of the Imperium, seeing what lay beyond, and using their null powers to remain unseen by the Ruinous Powers, resilient to the taint that later took so many of the other Space Marines to evil. They were deleted from records to maintain their secrecy. At some point, for unknown reasons, they all but disappeared, and the last few (they were never a large Chapter) went into a stasis sleep, with their Primarch, only recently being rediscovered by, as yet unidentified means.

Certainly, I have a bit more to work on, but have a pretty good idea of how they'll work. As I'm not currently running anything DW, I don't need to finish them, but if I did run it, I might have the team discover the stasis tomb they have been sealed in for all these millennia.

That's a really cool Idea!

My own thoughts on the lost Primarch's was that they were found so late during the Great crusade that they had no impact upon it. As in they were still forming/consolidating their power when the Heresy broke out and as such played no part in it.

Thus when the Heresy was over they started to help the Imperium but showed up as 2nd founding chapters closely associated to similar chapters.

The game I'm running has on such chapter/legion running around. But as another spanner in the works the 'Primarch' wasn't a Primarch but a Matriarch. thus her name wouldn't show up on the list of Primarchs, but on a separate list that may have been lost during the Siege of Terra.

 I have been toying with the idea that the two lost primarchs and there legions where not so much lost as sent so far from terra in the search for the remenants of humanity that no communication would be possible and the emperor may have lied about there fates purely for there own safety and to provide humanity with a ultimate last hope for itself. Two primarchs and there legions along with massive support sent out side of our galaxy to search out those members of humanity who during the peak of human expansion braved the seemingly infinite void to other galaxies. The emperor hid there existance to protect the secret that humanity had once traveled beyond our own galaxy even he was unsure what humanity may have become out there, as well as to provide a final hope that even if the worst should happen here perhaps humanity might live on. 

I was considering this would go along side the emperors death and in his final moment the astranomican flares guiding the lost legions home, coinciding with there return I even toyed with the idea of the recreation of the fallen traitor legions as chapters under there old colors, taught there history and sworn to 10,000 year long crusades against there fallen brothers.

 Just kicking around an idea, since I'm stuck at work on the 4th here. If anyone likes any of this feel free to lift it for your own use. Comments are also welcome. I'd almost started my own thread, then remembered this one and thought it would fit better here.

What if one of the lost legions, say XI for the arbitrary reason that the letter X stands for eXtreme, were actually the core of the Legion of the Damned. In this incarnation, they'd be sort of the 40k Space Marine equivalent of the Night's Watch from Game of Thrones. Perhaps their original mandate was to operate outside of the Imperium's bounds as an interdiction force.

I haven't seen the new stuff on the Legion of the Damned in "Honor the Chapter" yet, so I don't know if there's anything in there fluff-wise that would cause a problem. I'll edit and clean this up as new things occur to me, but for now it'll be a bit rough.

*Legion XI - Interdictors

*Primarch - Horatius (Status - TBD)

*Role - Guarding the borders of the Imperium, "holding the line" against unknown threats

*Tech - Mix of Heresy-era equipment, sprinkled with lesser new equipment from "adopting" reinforcements; possible archaeo-tech to explain LotD resilience, etc.

*Redacted from Imperial Records - Due to the the Heresy, this Legion was stricken from records to protect it from being attacked from the rear by supposed 'allies'. (Decision possibly reached with Horatius' knowledge, possibly worked out with the Emperor. The Legion knows it can never come home, but that their service is vital.)

*Recruitment - As a fleet-based legion, the Interdictors pull recruits from any suitable world. Additionally, any Marine forces they discover that would otherwise be lost to the void (such as the Fire Hawks) are drawn into the fold if willing, or possibly mind-wiped/sworn to utmost secrecy.

*Livery/Heraldry - TBD/Legion of the Damned colors

*Strength/Deployment - Scattered thinly along the borders of the Imperium, due to the vast space covered, precise operational numbers are unknown. Depending on threat levels detected, may operate in units ranging from a couple of squads to company-strength, though this leaves large stretches undefended, or only lightly covered.

I'm sure there are other things I'll think of. I'll add them as they come up. 

**EDIT #1: The "warp contagion" story with the Fire Hawks could be a cover story to ward off too much in the way of investigation. No one wants space cooties.

 It may just be that these chapters where never found.  The emperor may have written off finding them as Horus started attacking.  They may be like the grey knights a hidden force that only have contact with certain sections of the imperial and the records destroyed in order to keep them hidden 

Narvask said:

They were found, because they had statues in the Primarch's apartments, on Earth. There's a novel where Dorn is chatting with Malcador the Sigilite, and they mention it, upon Dorn musing that it would have been helpful to have 2 more Legions to fight Horus. The renegade Legion Primarchs are still statued there, even today, I believe tarped over, but the Lost Two have had their statues broken. They might exist in secret, today, like the Grey Knights, either hunting down enemies, or following the edge of the Imperium, routing for threats (if the Nids didn't thus find and eat them), but they were found, and the Emperor did SOMETHING with them, and their Primarchs. We don't get to know what, because it gives us freedom to add to the story, or some such.

An interesting possibility is raised by a listener of "The Butcher's Nails" about the two lost Primarchs:

http://www.bolterandchainsword.com/index.php?showtopic=255741

 I resurrect this thread!  

I always thought the lost Primarchs were just lost to the warp.  They were scattered by the Chaos Gods - they were lucky to survive at all, no matter how superhuman Avatar punching they are.  

On the other hand the failure idea is good too.  Maybe a combination of the two - they didn't survive the passage because they were in some sense failures, unable to withstand the terrible energies of the warp.  

I kinda like the idea that I read and heard about, that the warhammer fantasy world is actually a planet in the 40k universe. The elves (eldar) were put there to defend against some important threat long ago or something and humans suddenly appeared. There is a warp gate on the planet which chaos appears from and the world is surrounded by storms which would keep it from the eyes of the emperor.

Also, on this world they had a human champion called Sigmar, who ended up dying and becoming a "god". This god-like figure seems like it could fit very well with the description of a primarch. I haven't read it all in detail yet but I kinda like the idea, though as he died he would now be lost.

As for the other one I prefer a genetic failure probably, though there are other options as well.

As for the approach about one of these two primarchs wanting the emperor to step forward as god, we already have one of those. The Word Bearers had that role and fell, so another legion with the same idea doesn't appeal to me at least :)

Same for the navigators really, the thousand sons are the warp experts of the legions and they also fell. Had there been another legion who used the warp and disappeared or something, the story would have been much different I think. They would have known more about the warp and it's dangers probably.

I like this thread.

If a GM wanted to play around with a lost Primarch, and wanted to court canon even though it really wasn't, I'd recommend the Forge World chapter, Red Scorpions.  http://www.forgeworld.co.uk/Warhammer-40000/Space_Marines/Red_Scorpions

I really like Forge World's fluff for them, there models look cool, and because it's Forge World it feels a bit more canon to me.

 A few points from the Horus Heresy novels so be warned of [[SPOILERS]]:

• Leman Russ is described as the executioner in regards to the role of each primarch. This combined with Rogal Dorn's refusal to discuss the absent two Legions suggests at least one of them was essentially executed by the Space Wolves. Or it may be that Leman Russ personally executed another Primarch and the Legion was absorbed into the Ultramarines.
• The mention of one of the Primarchs being mutated and corrupted before being finishes rings true - several books discuss visions of the gene lab where the Emperor made the Primarchs, and during this vision one of the giant glass tubes that is growing one of the Primarchs is damage.
• The Emperor acknowledges in visions had by an astropath in The Outcast Dead that he is both Omnipotent and Omniscient, but that the trouble with these powers is that he can't be both at the same time. This suggests that early on the Emperor focussed more on his raw power in constructing the Primarchs, Legions, Crusades etc but that as time went on and the two Legions were lost/executed/absorbed he switched to more divinatory abilities to try and predict what would happen during the ensuing Heresy.
• The Emperor began work on the Golden Throne not as a life support machine as it ended upbut as a device to control the Web-way (the area that the Eldar use to travel interstellar distances safely from the powers of the Warp) in order to better control and protect the Imperium. His plan for Magnus to take control of the throne (as he knew it would be a permanent job, and he himself was too vital to the Imperium) shows that some of the Primarchs were designed from the start for consuming, destructive tasks.
• Mention of the two lost legions being similar in design to the Grey Knights is incorrect - the Grey Knights were set up in the wake of the Horus Heresy by loyalist marines from the Ultramarines, several traitor legions including the Death Guard, Luna Wolves and World Eaters, and the numbers from  Sisters of Silence. All of these founding members had first hard experience of fighting Chaos and the taint it can bring and were deemed pure enough to be involved in the creation of a new gene seed, though this last point is conjecture.
• Also to note that the Legion of the Damned are made up of the remnants of Fire Hawks chapter and not the lost two Legions as someone conjectured javascript:void(0);/*1349274432912*/

Kasatka said:

Although the inclusion of LotD in the Honour the Chapter, with the DW time-line being set prior to the Fire Hawks being lost (In fact Fire Hawks are also present in Honor the Chapter) suggests that there must be at least another chapter that forms the  Legion of the Damned.

Throughout Honor the Chapter, there are clips of narrative about a time-shifted ship from the future warning others not to approach due to some warp-disease, which leads into tales about the Legion of the Damned showing up, which sounds like it's still the Fire Hawks, some of which are in the wrong time because the Warp and stuff.

HOWEVER, it goes on to say that witnesses describe their heraldry as having either a sable cross on a field of some color I can't remember, or a cross on a sable field (don't have the book with me right now), which is not at all the heraldry of the Fire Hawks, which have a, ya know, firey hawk as their symbol according to Lexicanum. Notably, the Fire Angels have a cross in their heraldry, though Sable doesn't seem to be in their color scheme, so I don't know if that's an inconsistency in the book or whether there are other Legions of the Damned.

 If you read the Space Marine Battles book: Legion of the Damned, a description is given of a ship that is presumably controlled by the LotD. I don't have the book with me but as far as I remember the ship is described as an Aquila larger than the largest Imperial Starship, completely gold in colour, bristling with weapons and seemingly in possession of a Nova Cannon the likes of which has scarcely been dreamt of in the Imperium. I have done a reasonable amount of back-reading into 40k fluff and I don't remember any mention of the Fire Hawks having anything like that… And that Wikipedia page seems to presume a lot about the LotD considering they are one of my favourite things from 40k and I have never even heard of any of that nonsense about the battle franzy illness and after that I stopped paying attention to be honest because the guy who wrote that page seems to have taken it upon himself to make up a load of waffling crap