Liber Proditor Armorum
The full content of the work is unknown, but it focuses on the Iron Warriors' use of armored units. The text has been widely discussed, due to its insight on the Iron Warriors' practice of creating a deep union between crew and machine, especially Predator tanks. While Imperial forces often engage in crew-machine unions to pilot military vehicles, the Iron Warriors' practice forms a permanent cybernetic bond between vehicle and crew. Techmarine Blane notes that Iron Warrior crew members are commonly sealed into the pilots' compartments, similar to being interned inside a Dreadnought.
The Liber Proditor Armorum has demonstrated a practical value for engaging Chaos Space Marines. In the Battle of Ramisen Point, the Imperial Fists utterly defeated an Iron Warriors armoured advance with Devastators equipped with targeting data that made use of the text.
The work was considered for inclusion within the Codex Astartes, but denied by the Iron Hands, who engage in similar practices to those described by the text. The Iron Hands maintain that their rejection was intended to keep the information within the Liber from falling into the wrong hands.
The text has also been criticized as reflecting the characteristics inherent to the Geneseed of the Imperial Fists, in particular the tendency towards self-imposed penance and contrition. How these characteristics are considered by detractors to negatively affect the work is not explicitly stated.