The first expansion for the new edition of Warhammer: The Horus Heresy takes us back to Isstvan V for a closer look at the infamous Dropsite Massacre, introducing new perspectives on this dynamic battle and three new units for Legiones Astartes armies to try out on the battlefield. This 48-page softback book also includes a new Legendary Mission evoking the struggles of the first wave to attack Horus’ stronghold, so you can see how your own forces would have fared in the Urgall Depression.