What space marine chapter would you send to stop a mass system-wide imperial guard betrayal in Slaanesh's name?
writing a fanfic for a Slaaneshi IG regiment i'm working on, I'm not super well versed in the successor chapters and I'm curious.
(However, the attempt to stop the betrayal fails in the lore, so maybe also legions who would be destined to fail could be good. educate me!) image of IG regiment
Edit: I should have been more specific! My bad, by “regiment” I mean more of a planetary defense force, multiple machine, ship, and infantry detachments on multiple worlds, and they are making efforts to summon demons and communicate with leftovers from the black crusades, this is much more of a significant threat then just an infantry regiment or a tank battalion, it is intended to be a secession of these 5 worlds from the imperium in chaos’s name. Thanks for diving so deep! If you want to talk lore in more detail dm me I’m down