Backround:
The Legion are afflicted by a warp contagion that destroys their sanity; as it progresses their bodies decay, but they grow in supernatural strength. Each Marine is rapidly approaching the moment when he will succumb to the contagion. Combat can initiate the final stages of the disease, in which the Marine reaches a peak in power and enters a berserker state.
Organization & Combat doctrines:
The Legion has no formal organisation - it fights as a single body of troops. The only tactic possible to such a formation is to steam-roller over the enemy by a steady advance.
The Legion is not a part of any Imperial force, and employs an unusual modus operandi. Apart from driving them insane, the contagion heightens their psychic awareness considerably. One result of this is the way in which the legion selects and attacks targets. These matters are left entirely to the process of divination provided by the mystic Emperor's Tarot. This tarot is supposedly bound within the psychic will of the Emperor and is used throughout the Imperium as both a pastime and a form of divination. It is an undeniable fact that attacks seem to fall in 'the right place at the right time'. The Legion of the Damned certainly believe themselves to be directed by the Emperor - and who is to argue!
History:
In the year 963.M41 the Fire Hawks were sent to the Crows World subsector against Eldar pirates. The entire chapter-fleet, including the chapter's mobile space-fortress Raptorus Rex, made a successful warp jump from the Piraeus system 120 light years from Crows World. The five ships, over eight hundred brethren, and two thousand other personnel expected to reach Crows World within no more than 12 hours. They never arrived.
Twenty years after the event the chapter was officially declared lost in the warp and presumed destroyed. The great Bell of Lost Souls tolled a thousand times, and it said that the Emperor himself ordered a Black Candle to be lit in the Adeptus Chapel of Fallen Heroes.
On 9667986.M41 a routine Imperial patrol passed through the Ork held system of Jakor-tal. The squadron uncovered altogether unexpected scenes of devastation. The limited facilities available to the patrol could uncover no clue to the identity of the attacking forces. The incident was noted and passed into the records of the Administratum.
A rash of similar incidents within the same and adjoining sectors aroused the interest of the Inquisition but no sign of the intruders was discovered for almost a year. Then, a patrol ship in the Maran sub-sector narrowly avoided a collision with a space-craft at the Cift jump-point. The patrol ship was entering the Cift system as the unidentified craft was leaving. Alerted by the close encounter, the patrol crew scanned the entire jump-area and discovered two long cylindrical objects within the intruder's projected flight-path. These were hauled aboard and proved to be standard space-coffins without identification markings.
The coffins were shipped back to earth and opened by the Adeptus Mechanicus. The coffins themselves were identified as belonging to the Absolute, one of the spacecraft from the vanished Fire Hawk fleet. Inside were the armoured remains of two Space Marines. The unconventional armour colours and unofficial insignia puzzled the investigators, but serial numbers tallied with equipment made by or issued to the Fire Hawks. The armoured suits were expected to house members of the lost chapter, and were carefully broken open. The bodies within were human, but further identification proved impossible due to their advanced state of decay.
Almost a year later a besieged Imperial research station received unexpected help. The garrison had been attacked by Ork pirates. After three hours of fighting the situation looked hopeless. Then, without warning, the Orks found themselves attacked from the rear. Within half an hour, several hundred Orks had fallen to the mysterious, power armoured figures. Then, as suddenly as they had appeared, the warriors vanished. This time they left behind a banner - the gnarled chapter flag of the Fire Hawks - and inscribed upon it was the motto In dedicato imperatum ultra articulo mortis (For the Emperor beyond the point of death). As well as the banner there was a recorder and sundry other sealed items. These were shipped to Terra.
The Fire hawks Fate:
From the data contained in the recorder the Administratum was able to determine exactly what had happened to the lost chapter. Following their warp-jump the entire fleet had been caught within a warp-storm of terrific intensity and forced to endure the attacks of powerful warp entities. Ship after ship was destroyed. Soon only one craft remained. By a daring warp-exit manoeuvre the craft burst out of warp-space, emerging far in the galactic east, thousands of light years off-course and beyond even the psychic light of the Emperor.
The original survivors numbered two hundred brethren. All gene-seed had been lost, all initiates killed, and most of the chapter's masters were gone. None of the ordinary human staff have survived at all. To make matters worse the brethren had changed. This change became more obvious over the next few months. Skins began to blacken and blister, flesh began to fester and putrefy. Slowly they began to die. Within days of the transition into normal space it became obvious that the chapter had been exposed to some form of dangerous mutation or disease. It took many years to navigate a way back into the Imperium, during which time almost half the brethren succumbed to the malady. Those who remained were no longer sane. Pain and despair had driven even their hardened minds beyond the point of rationality. Doomed to agonising deaths, they gradually became obsessed with their fate. Now they only wanted to die. But they were still marines, still loyal to the Emperor and humanity. They would not die without a purpose.
So began the unstoppable war of the Legion of the Damned! The marines elected to remove all insignia from their armour. Instead their armour would be black, decorated by each brother with whatever emblems of death he chose. Most brothers employed a similar theme - skeletons, bones and skulls.
All ranks and companies were abolished, most of the chapter's officers were already dead and the remaining warriors were too few to make up a fully functioning chapter hierarchy. All brothers were to be equal before death - levelled by the certainty of their assured extinction. The warriors decided to expend their lives attacking enemies wherever they could be found. The disease had robbed them of their sanity, but not their loyalty!
Overview:
The Legion comes unannounced on the battlefield and is unlooked for. They are wreathed in a spectral fury which descends upon the foes of Mankind where they battle them without outcry or war shouts until the enemy is scattered and the day is saved. Once victory is found, just as they mysterious enter the battlefield, they disppear again to whatever hellish realm they came from.
The armour of the Legion is black as midnight and marked with symbols of death and damnation. This includes skull grinning cheerlessly from helm and boltgun while bones twist admist the flames of purgatory.
Fluff terminated.
That was what i could find fro lexicanum
Idea:
Ship after ship was destroyed. Soon only one craft remained. By a daring warp-exit manoeuvre the craft burst out of warp-space, emerging far in the galactic east, thousands of light years off-course and beyond even the psychic light of the Emperor.
The original survivors numbered two hundred brethren.
ok, records are scarce and all were believed to be destroyed, it says 1 ship made it out, but this is unconfirmed, what if another ship made it out without being noticed?
theres a very small chance that the marines could have escaped, so my idea is to create a chapter similar to the fire hwks and the legion of the damned, so they will have black armour decorated with flames and bone, yet the disease only made them stronger, thier numbers are still 200, and from this they have established a heirarchy.
thier commander has taken over as a leader (or new chapter master)
thier bodies have
de-composed, but thier essence is still in thier power armour, marching on relentlessly to carry out the orders of thier emporor and destroy the traitor legions.
ok, seems far fetched, but its an idea and something to work with for now until i can find an idea or more fluff to elaborate more.
reasons for this idea:
I love legion of the damned, yet they are becomming too common now a days.
black power armour decorated with flames and bones looks amazing.
an army with pure troops and maybe a dreadnought or 2 would be fun to play.
Ideas on units:
all vehicles other than the odd dreadnought are out of the list.
bikes are gone too.
they will be led by a chapter master and a chappy.
no scouts will be included as no skin will be shown on models.
all models will have closed helmets.
no purity seals or other insignia will be included, so the imperial eagles will be removed from all armour.
for the hell of it:
a unit of vanguard (i know they are very points heavy) with power spears (power sword on a long haft with a single wing on the base of the sword, ill draw something up soon)
why? since they were pretty much a sub chapter of the fire hawks i thought a unit of jump infantry would be fitting.
Final notes:
i am sorry for any incorrect spelling or grammar, i have checked, but chances are i have missed something somewhere.
i dont think i have ever used this many words in a single post in my life!
as usual, C&C is welcome, and any ideas or ways to improve this fluff wise or model wise are appreciated.
And, some complimentry pics
(you deserve a break from that reading)
and a nice Dawn of war pic
Suffused with the dying memories of Sanguinus, the warriors of the Death Company seek only one thing: death in battle fighting against the enemies of the Emperor. 
Renegade Guardsmen