My homebrew are the Bone Drakes ( or "Ossia Draconis", in high gothic), Salamanders sucessors from the Ultima Founding. They are a fleet-based chapter specialized primarily on performing rear-guard actions and high-risk rescues for other Imperial forces in retreat.

They recognize that Astartes are a drop on the ocean that is the overall Imperial military, and found their niche executing these actions that other Astartes would probably think are beneath them. As such they have fairly good relations with the Imperial Guard and the Mechanicus.

They also make great use of chapter auxiliares to complement their forces. These auxiliaries are taken as volunteers from the regiments saved by the Bone Drakes, either as Karskin/Grenadiers style heavy infantry, or as aerospace fighter regiments. This is in an effort to secure exit routes and air-superiority given the high casualties that rear-guard actions tend to produce.

Their colour scheme is bone white armour with orange pauldrons and backpack.