I've made Horus again, but she's back to being evil again, joining the Ruinous powers to destroy the imperium of man, with some of her sisters also joining in destroying the imperium. 

Yeah, you got murked by the Empress because she thought you were a distraction to Hours and a liability to her and the great crusade. So you got smacked, and Horus isn't happy about that. 

And this isn't very accurate; it's not real! I'm making it up because I don't like how horus turned bad in the real lore, so I'm making this one up.