Warhammer 40,000 Codex: Genestealer Cults
The essential book for all fans of Genestealer Cults!
Contains all the rules you need to command a Genestealer Cults army. Includes a card sheet containing 28 Cult Ambush markers and a 9" range ruler, used when setting up Genestealer Cults in ambush.
Brood Brothers rule allows you to include an Astra Militarum detachment in a battle-forged army and includes datasheet for the Tectonic Fragdrill.