Adeptus Titanicus: Traitor Legios 

This 176-page hardback book contains:
– Background for Traitor Titan Legions and Knight Houses
– Revised rules for assembling your battlegroups
– Rules for 16 Traitor Titan Legions, including Legio traits, Stratagems, and wargear
– Rules for 12 Traitor Knight houses
– 19 different maniples to use with your Titans
– Allegiance rules for Traitor Titan Legion Battlegroups, Questor Traitoris, and Questor Mechanicus
– Background and rules for fielding Corrupted Titans, mutated god-engines fielded in the latter days of the Horus Heresy
– 51 Stratagems for use by Traitor battlegroups
– 11 Titan upgrades
– A comprehensive list of weapons available to each Titan, including weapon traits not featured in the core rulebook