Hey guys thanks for the input! Here some ideas I’ve been working on, thoughts are much appreciated.
Their Home planet is so far from its star its surface is a frozen wasteland. However a vast network of caves riddle its crust. Warmed by the planets core, the local population make there home here, building cities in the largest caverns. The planet is rich in mineral resources and the locals expand the cave network chasing them.
A flaw has developed in the chapters gene-seed, the occulobe has become overactive. The cause is unknown the effect however is obvious. It’s increased potency leaves an aspirants eyes nearly entirely white, while giving the marines perfect night vision it increasing their sensitivity to normal light. The chapter has incorporated this into their following of the promethean cult, using the pain caused by staring into the heart of a bright flame as a focus while meditating.
Given the environment of their home world the marines prefer cramped quarters such as urban battlefields and ship boarding actions. They make heavy use of flame and melta weaponry due to this preference much like their parent chapter. Though they are no less effective in other theatres of war, but due to their flaw it is rare to see a full battle brother without a helmet. The scouts however are limited to nocturnal operations where possible, making full use of their enhanced night vision.
In my head I have idea that early in they history they have an encounter with a chaos warband that appears to be active near their sphere of operations. The warband has invaded a planet and summoned a greater demon. The chapter brings their full might to bare, eventually liberating the planet. The master of sanctity and his retinue mange to kill the greater demon but all but the
MoS die and he is mortally wounded and interred in a venerable dreadnought and is still around today. The remains of the warband make their escape.
Seeing as I have the dark imperium box I was going to make it a nurgle warband lead by a lord of contagion which I could develop and paint up next. Have him seeking to raise to daemonhood and the loyalists disrupted him the first time. Over the following centuries/Millenia the continue to encounter each other, becoming hated foes known to one another.
With the arrival of the great rift the current chapter master on board the chapter’s battlebarge is lost in the warp or on the far side of the rift. With a few companies active in other theatres of war only the reserve companies are manning the fortress monestary with the chief librarian. Lord of contagion and co. return, with the intent of sacrificing the planet for his rise to daemonhood. Outnumbered they put out a call for aid, derminted to save as many civilians as possible they work closely with PDF collapsing tunnels creating choke points and fight a slow withdrawal, delaying the warband as much as possible. Eventually they are saved by the arrival of elements of the indomitus crusade. With so few marines remaining they welcome the influx of primaries marines. Also in there somewhere a rematch between the greater daemon and the now dreadnought
MoS .
Thanks for the help!