Bolter and Chainsword release The Dornian Heresy Volume 1
From their website:
This premier issue is devoted to chronicling something a little different; a twisted alternate timeline in which Warmaster Horus was able to cast off the daemonic influences that sought to possess him, and where the Ruinous Powers were instead forced to corrupt Rogal Dorn to overthrow the Emperor. The Dornian Heresy is the tale of an alternate universe where choices, sometimes large, sometimes small, have led to the familiar primarchs and legions meeting very different fates. For instance, how different might things have turned out if Sanguinius had instead been found and raised by the mutant tribes of Baal, or if Angron’s first meeting with the Emperor had been as an honourable ally against the slavers at Fedan Mhor?