I might be wrong, but I'm sure I found rules somewhere for player characters to join or leave a horde as a half action. Can't find those rules anymore though. Am I delusional?

I've never seen anything like that, ever.

Thaddux said:

You are not delusional.

See pg 350 of the Black Crusade Core Rules, the section titled HORDE VERSUS HORDE COMBAT , for the rules regarding PCs joining with and fighting as part of a Horde.

Thanks.

Could have sworn there was more to it than that though. Never mind, maybe there will be something in one of the upcoming books.