The Thirteen Commandments of Iron are a litany of 13 rites of honour that are used as a supplement to the Codex Astartes as a rite to follow in order to prevent heresy. They were written by Iron Warden Urexus Banesword, re-founder of the Iron Scorpions Chapter, after seeing that the Codex written by Robute Guilliman could possibly not be enough to ensure preservation from the taint of chaos. Today it is mostly in use by chapters that have experienced, or have dwindled at the brink of a heresy (though not all of them) to ensure that it would not happen again.