Board Thread:Warhammer 40k General Discussion/@comment-14745711-20140911102114/@comment-6078851-20140914152634

emps was created by the mass suicide of psykers to imbue a single being with all their souls, but that being still had to be born to a family.

the warp can and does send things back in time, and so by extension the gods, if united, could theoretically send someone back in time. there's a couple of instances but specifically i refer to the abortive ork waagh where the ork forces were 'spit out' of the warp just before they actually entered it. the ork warboss, who had a gun he loved, then had the very orky notion of killing his previous self in order to have a second gun he loved.

codex quote: "the ork warlord grizgutz, a noted kleptomaniac, launches  his waaagh! into the morloq system. whilst using warp travel to reach their quarry, grizgutz and his warband unwittingly travel through time and emerge from the shifting chaos of the empyrean shortly before they set off. grizgutz hunts down and kills his doppleganger, reasoning he can have a spare of his favourite gun. the resultant confusion stops the waaagh! in its tracks."