"Fire hungers. It hungers to burn, and when unleashed it knows no true master, it devours without reason or mercy, until it has consumed everything it touches. Such a fire is war."


The Horus Heresy: Book Three - Extermination is the third book released as part of Forge World's Horus Heresy Series of campaign and army books that takes place during the Horus Heresy. The book deals with the end and aftermath of the Drop Site Massacre, the Battle of Paramar, and the Battle of Phall. The book contains rules and special characters for the pre-Heresy Alpha Legion, Imperial Fists, Raven Guard, and Iron Warriors Legions as well as an updated Space Marine Crusade Legion army list, and a Mechanicum army list.

Official Synopsis

The third and final part of the Isstvan trilogy, this book details the aftermath of the Isstvan V Drop Site Massacre, and two other major battles fought between the Loyalist and Traitor Legions as the Horus Heresy swept out from the Isstvan System and into the wider Imperium of Mankind: the Battle of Phall and the Invasion of Paramar. Also featured are the background and game rules for the four Space Marine Legions covered in this book: the Alpha Legion, Imperial Fists, Raven Guard and Iron Warriors, and a Mechanicum army list, plus new campaigns and vehicles.

This lavishly illustrated, full-colour, 285 page hard cover book is leather bound with metal corner clasps stamped with the Imperial Aquila, and features a red ribbon bookmark and foil-edged pages as well as an embossed cover and spine.


The following is every section contained within The Horus Heresy Book Three - Extermination:

  • Preface - The preface of this book, and all other Forge World Horus Heresy books begin with a foreword by the in-universe "author" of the book, an unknown individual who signs with the letters AK.
  • Imperius Dominatus - A Great Crusade -era map that covers two full pages, and includes the names of many notable worlds and locations.
  • The Ashes of Isstvan - This short section describes the immediate aftermath of the Traitor Legions' victory on Isstvan V against the Loyalist Legions of the Emperor . A massive amphitheater and dais was constructed form the corpses of those loyal to the Emperor, with the Traitor Legions and their Primarchs gathered to listen to a speech by Warmaster Horus where he assured them a swift victory against the Emperor and those who followed Him. During the speech the structure of corpses was set alight, choking the Urgall Depression with ash.
  • The Victory is Vengeance & Blood in the Void Expansion - This section contains missions that allow players to re-fight in two of the key conflicts described in the book, the first being the Raven Guard Legion's ninety-eight day battle for survival on Isstvan V and the second being the Battle of Phall. Included in this section are updated rules to fight a Zone Mortalis battle.
    • The Victory is Vengeance Campaign
    • Strike Forces
    • Tactical Strike Warfare in the Horus Heresy
    • Victory is Vengeance Campaign Missions
    • Legendary Mission: Deliverance
    • Blood in the Void Expansion
    • Zone Mortalis Boarding Assault Mission - Void Strike
    • Zone Mortalis Boarding Assault Mission - Wrecking Mission
    • Zone Mortalis Boarding Assault Mission - Salvation
    • Zone Mortalis Boarding Assault Mission - Killing Blow
    • Zone Mortalis Boarding Assault Stratagems
    • The Taking of the Contrador
  • The Taghmata Omnissiah - This section contains the rules and units needed for building Mechanicum force, either as a standalone army or as an allied detachment to a Legiones Astartes force.
    • The Taghmata Omnissiah
    • Using the Taghmata Omnissiah Army List
    • Mechanicum Warlord Traits
    • The Belicosa Potentis Omnissiah Organisational Structure
    • Taghmata Omnissiah Wargear & Special Rules
    • Cybertheurgy
    • HQ
    • Elites
    • Troops
    • Dedicated Transport
    • Fast Attack
    • Heavy Support
    • Lords of War
  • Space Marine Legion Crusade Army List Additions and Updates - This section includes rules that expands upon the Space Marine Legion Crusade Army List found in The Horus Heresy: Book One - Betrayal.
    • Additional Special Rules for Heresy-era Gaming
    • Fast Attack
    • Heavy Support
    • Lords of War
    • Fortification
  • Afterword - An afterword about the Horus Heresy and Warhammer 40,000 by the Forge World Studio.

Included Legion Specific Army Rules

The following is a list of included unit rules that are specific to a certain Legion only:

Included Non-Legion Specific Army Rules

The following is a list of included unit rules that are able to be taken by all Space Marine Legions:

Included Mechanicum Army Rules

The following is a list of included unit rules that are able to be taken by a Mechanicum Army:


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