Digging stuff up in the Lexicanum, I ran across the Exorcists-composed Chapter (
http://wh40k.lexicanum.com/wiki/Exorcists)...and don't really recall them besides some of the early editions. Are they still part of canon or, like Malice the fourth Chaos god and Warhammer fantasy connections, have they been long abandoned?
Also...666 verses from the...Book of Exorcisms?
This one I really did not know. Where does it come from? Official manuals? Books? I had never even heard of it before...