Originally Posted by maglag
Searching for a solution among the Librarium of the Ravenspire, Corax found the ancient books of genetic research providing the techniques used to create the first enhanced warriors of the Emperor, those techniques Corax duplicated to create Spaces Marines at a frightening rate.[/i]
Corax created his super marines with the tecniques used for the first enanched warriors of the Emperor. Which would be either Thunder Warriors or Adeptus Custodes. Not the primarchs.
In Deliverance Lost
, Corax goes to Terra. He speaks personally with Dorn and with Malcador. Runs through a maze and one of his psykers opens a psy-locked door and pretends nothing ever happened. Because if the psyker admits what he did - regardless that he needed to to get to the DNA - Corax would be forced to execute him due to the decree of Nikea.
Oops. That's not in Lexicanum. Didn't happen.