Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

I was reading through the lore in the codex and it explains how genestealer cult manipulate and control the population of whatever planet they are on, which I assume is why they can ally with imperial guard (blood brothers special rule). However, this lead me to consider other imperium factions, because lore-wise some of them have no particular psychic defenses right? So theoretically couldn’t genestealer cult ally with and manipulate other imperium armies? Please comment thoughts. Thanks.

The Brood Brothers rule represents local PDF who are part of the Cult, rather than mind-controlled Guard. There's AdMech GSC in one of the Cain books (but they have to skip 'upgrades' or they'd be found out).

Genestealers can control just about anyone - they 'take over' a Grey Knight in Incorruptible, for example.