Went back to the Horus Heresy to read Praetorian Of Dorn because it's the book Alpharius dies in and Alpha Legion are my favourite "traitor" legion and I expected shenanigans.
I was not disappointed as at the start of the book sleeper agents on Terra dug up secret underground storage tanks that contained hibernating Alpha Legion space marines that the legion had buried there literally years ago before the heresy even started and they all have different conflicting missions.
I fucking love Alpha Legion.