The Horus Heresy Age of Darkness Rulebook will incorporate previous FAQs for 7th Edition and introduce army construction sections using the Horus Heresy rules rather than 7th Edition standard rules. There are changes in balance based on community input, invisibility has been replaced, and use of melta-bombs has been updated. Horus Heresy Rulebook contains all the rules, reference material and lore for specific Legions (or Mechanicum, or Crusade Imperialis) in one volume.
The new rulebook is compatible with all current Horus Heresy books and expansions. Release date and MSRP were not announced.
GW recently released The Horus Heresy: Betrayal at Calth standalone miniatures game (see “Review: 'Horus Heresy: Betrayal at Calth'”).