The Star Phantoms are a Loyalist Space Marine Chapter of the 23rd Founding created in the early 38th Millennium from an unknown origin. They took part in the final days of the Badab War and the final assault upon the Astral Claws' homeworld of Badab Primaris, helping bring the war to a successful conclusion.- exerpt from Warhammer 40k Wiki (and tehrefore Forgeworld Books)
The Star Phantom is one of those chapters who doesn't draw masses. Out of the Badad War, they are most probably the least played army.
True that the Forgeworld book doesn't gift them so much but the looks... That paint scheme is awesome and what Forgeworld did with the illustration is simply WOW.
They will complement the Blood Angels nicely in my opinion and their paint scheme is something that I've wanted to give a try to for a long while now.