Board Thread:Warhammer 40k General Discussion/@comment-71.91.63.134-20150920063835

I would like to have a discussion on the lost legions and their primarchs, and their fate. I know that the intetion for the two lost legions were created by GW to let people make their own legions. It is a little disapointing GW hasn't gone in to depth with the story of the legions, but at this point anything they make would not live up to expectation. So after reading various therories on the legions the one that struck me the most is that the legion was sent to hold off the tyranids until the Great Crusade was completed. At which point the Emperor would have sent the others rto finish off or at least firmly deny the tyranids access to the Imperium. This in my opinion is possiable as their are charectors who can foretell the future. This walso works well with the  theories that the lost primarchs were killed or imprisoned for some offence to the Imperium. As all traces of their legions disapeared it cold hint they were sent to atone for the acts of their gene fathers. All this fell apart though because of the Heresy and at somepoint the lost legions were overwhelmed by the tyranids and they began their onslaught on the galaxy. I would greatly enjoy to hear your thoughts on this or any other theories you have. 