Backstory
History:
The Stormbreakers are a product of the Ultima Founding, but not an intended one. Many space marine chapters trapped behind the great rift received Primaris reinforcements, gene-seed and the secrets to the creation of this new breed of transhuman warriors. But any trip through the warp carries risk, especially in the Imperium Nihilus. One such vessel suffered a critical gellar field failure during transit through the warp and breached from it decades before they had initially departed. The vessel crashed on a remote planet near a previously charted warp rift made more unstable by the new warp rift bisecting the galaxy. The survivors of the vessel were few, with the majority of its bodyguard compliment dead. But some survivors remained.
The blighted inhabitants of the world Shadar'Mar discovered the crashed Imperial vessel and took it as a step in their culture's prophecy of the end times. But a group of youths managed to awaken some of the Dreadnought complement of the ship who had survived the crash. Moved by the people's story and determination, the doomed gene-seed and secrets of the Astartes were bestowed by the vessel's survivors to the inhabitants of Shadar'Mar. They became the first Astartes of the Stormbreakers, and fought with limited armaments and their people's latent psychic might against the spew of daemonic forces from the Braizan rift.
When vessels of the Imperium Nihilus regent re-discovered the world of Shadar'Mar they found the crashed ship and a bastardized version of an Adeptus Astartes chapter fighting on the world. The Chapter narrowly avoided complete extermination for the circumstances of its foundings and the dangers posed by the psychic potential of the recruits from its homeworld. In the indomidus era the Stormbreakers’ operations are largely confined to their home sector, operating from their fortress monastery of the crashed imperium vessel and limited chapter battle barges.
Organisation:
Brothers of the Stormbreakers chapter attempt to discipline their innate psychana through the swearing and holding of strict oaths, known as the Radiant Oaths. The oaths find their origins in the Chapter's home world's pre-imperial religion. The people would swear to one of ten Radiant Oaths, simple mantras guiding one's ideals and principles. Adherence to a particular oath would usually govern one's path and place in society, and keeping these Oaths was said to appease the good spirits of Shadar and ward away the demons of the Braizan Maw. The adherence to oaths is maintained within the Stormbreakers as a form of mental disciplining. On ascending from neophytes an Astartes brother will swear to one of the 10 radiant oaths. These mental disciplines form the basis of training that Stormbreakers use to control their latent psychic abilities, which they typically channel into their weaponry and battleplate. It is this energy that turns their unadorned ceremite grey power armour to a shifting, etheric blue.
While utilizing the core of Roboute Guilliman’s revised Codex Astartes as a framework for its organizational foundations, the Stormbreakers chapter is considered non-codex compliant. The companies of the Chapter are not separated by their individual oaths despite 10 oaths matching 10 chapter companies, a decision made to encourage flexible thinking in tactics and strategy. However it is common to find individual squads composed of those brothers sworn the same oath. In keeping with their home world's more primitive war-culture, close quarters melee combat tactics and assault squads are the most commonly found aspect of the Chapter's combat flexibility.
The functions of the Chapter Librarius and Reclusiam are combined in the Stormbreakers, and its numbers are greatly expanded. In addition to their traditional duties, Librarians fill the role of Chaplains, each swearing to one of the Radiant Oaths as all other brothers. Librarians however will not ever change their oaths. Battle brothers typically do not sway to a new oath, but the practice is not unheard of.
Each oath has a Chief Librarian, typically referred to as a Herald. They take up a new name and title reflecting the folklore spirit and their respective oath. These heralds travel between companies to ensure adherence to the immortal words and assess the company's psychic stability. These 10 heralds select the Stormbreaker's Chapter Master, and are considered almost equal in authority to the Chapter Master.
The most psychically inert neophytes are typically indicted into the ranks of the Techmarines in an attempt to better appease the Adeptus Mechanicus. Other more stable battle brothers who instead serve in battle or reserve companies are typically those who are provided when their ranks are requisitioned into the Deathwatch or sent to serve alongside other chapters, in order to conceal the breadth of latent psychana in the chapter.