Simultaneous Transmigration: From the Start, Boarding Six Thousand Sons of Vengeance

A man in Warhammer 40K, while transmigrating across the Myriad Worlds. Endless abilities become mine. My combat power stacks without limit. When I first transmigrated, you said I was just an ordinary Primarch. I didn't argue. But after fusing with the abilities of the Myriad Worlds, what should you call me now?! Father, please step back a little. I shall burn these Four Gods of the Warp to ash! (Featuring worlds from novels, anime, films, and television.)