When it comes to the Old Gods vs Imperium, no one wins. ... Cthulhu would win if the Emperor was just a exceptional mortal psyker, but he fundamentally is not. read more
second scenario: horus wins and basically becomes permanent warmaster of chaos, and leads his legions into battle against all the other races, before finally meeting his end vs necrons/tyranids. read more
This also includes"who would win" and broad"what if" scenarios. There's /r/warhammerwhatif for that. Rule 4b: Do not post just links (YouTube, Imgur, Bell of Lost Souls, etc). read more
Forgeworld's Horus Heresy: Betrayal book describes one of the War Hounds (Who would eventually be the World Eaters) first deployments against a group of renegade Thunder Warriors in a space station over Terra. read more