The Black Library is doing a series of novels that focuses on the Primarchs, starting off with Roboute Guilliman. The second one looks like its going to be about Leman Russ. Now that is one that has a ton of questions that i would like to read. The best part of these is, that the pre-order looks like the hardcover book is only $17.50! Im on that one. The release date is October 25th 2016
This was posted on Amazon
Roboute Guilliman (The Horus Heresy: Primarchs) Hardcover – October 25, 2016
by David Annandale (Author)
Launch title in The Horus Heresy: Primarchs series, a brand new sequence of novels from Black Library.
Long before the coming of the Imperium, the realm of Ultramar was ruled by Roboute Guilliman, the last Battle King of Macragge. Even after learning of his true heritage as a primarch son of the Emperor of Mankind, he strove to expand his domain as efficiently and benevolently as possible, with the XIII Legion Ultramarines as his alone to command. Now, facing a rival empire on the ork-held world of Thoas, Guilliman must choose his weapons carefully – otherwise his dream of a brighter future could be lost forever.