Warhammer 40,000 Core Rule Book Age 12+ A 368-page hardback, this is the essential book for any fan of Warhammer 40,000 – everything you need to know to collect, build, paint and play with Citadel miniatures. It starts with an overview of the Warhammer 40,000 hobby, covering the four areas of Collect, Built, Paint and Play, including descriptions of open, matched, and narrative play.