The Witch Hunters are the branch of the Inquisition tasked with rooting out heretics, mutants, and most importantly, witches from within the Imperium. Aided by their Chamber Militant – the zealous and uncompromising Adepta Sororitas, the Sisters of Battle – the Witch Hunters purge the unclean and wicked from the Emperor's realm. Codex: Witch Hunters allows you to field them on the tabletop battlefield.

Codex: Witch Hunters is the second book in our trilogy of Inquisition Codices (which includes Codex: Daemonhunters and the forthcoming Codex: Alien Hunters). When Andy and I were first handed this project just before Christmas 2002, we jumped at the chance to take a project from its earliest conception through to a finished product. It was a great opportunity for us, and we weren't about to let it go.

Codex: Witch Hunters was the first project for Warhammer 40,000 that would go through a new design process. The initial stages of this process required a number of people with a vast knowledge of the 40K universe to sit in a room and collect everything we knew about the Inquisition, the Witch Hunters, the Sisters of Battle, the Ecclesiarchy, and anything else that would be relevant in establishing this Codex.

The Sisters of Battle purge a world of Chaotic mutation.

As well as drawing upon existing material (which stretched back 15 years!), we threw idea after idea around the group, batted them about, and allowed every mad, insane thought its time in court. This process allowed our conceptual artists to go off and sketch out every bonkers idea they could think of, based on what had come out of our meetings and whatever insanity bubbled from the depths of their crazed minds. You never know what might come out of the maddest idea. Just check out Inquisitor Lord Karamazov's Throne of Judgment if you don't believe me.

As well as imagery, we needed to ask the big questions. Who are the Witch Hunters? Where are they, and what do they do? How and why do they do it? And, perhaps more importantly, what are the consequences if they fail? We knew that before we focused on the actual content of the book, we had to answer these questions. Even though the book could not possibly contain everything that would emerge from this process, it was important to establish as much about the Witch Hunters and their forces as we could before we put finger to keyboard.

The end result of this process was a wealth of conceptual imagery and reams of paper describing everything from how the Witch Hunters go to war on a planetary scale (complete with the colossal Cathedral on tracks) to the subtle differences between all the shades of grey that distinguish a Radical Witch Hunter from a Puritan one. It was enormous fun to take part in these meetings and spend entire days coming up with ideas and concepts for something that was essentially brand new. Once we were done, we could begin the process of actually writing the book.

Next: Designer's Notes Part 2.