Board Thread:Warhammer 40k General Discussion/@comment-25222488-20151025234507/@comment-18016240-20151115211853

Not really, remember that the only ones actively contributing to Ynnead's birth are largely the craftworld and maybe the maiden world Eldar, and that's only if their soul stones aren't destroyed after death which would send their soul straight to Slaanesh. The Dark Eldar have pretty much nothing to do with Ynnead. In fact they're pretty much constantly feeding Slaanesh no matter what they do simply because they need to cause pain and suffering to continue existing, so you have to balance the over ten thousand years of them continuing to torture people against the combined souls of the Craftworld and exile/maiden world Eldar, plus Slaanesh is being fed by all the humans and other xenos life that serve it now. That's a tall order for some newly formed whelp of a deity.

Besides that, even if Cegorrach were to help Ynnead out, remember that Slaanesh was able to wipe out almost the entire Eldar pantheon aside from him, Isha and Khaine, Isha was captured by Slaanesh to be his toy before she was taken from him by Nurgle (depending on what continuity you follow) and Khaine has been broken into a million pieces. Cegorach is the only active Eldar god, but I'd reckon that there's a good reason why he's sticking to the Webway and not trying to pick a fight with Slaanesh in the Warp itself. This isn't even mentioning that he's a god of trickery, not a god of battle, which means that he may not be a great fighter regardless.

If they get involved with Nurgle, that would mean picking a fight with two Chaos gods, and when the Chaos gods aren't being stupid they can be one of if not the most dangerous force in the galaxy (for example, the Horus Heresy), Nurgle is depicted as generally being more powerful than Slaanesh (though admittedly his power tends to wax and wane more than the other Chaos gods), so Isha's probably screwed no matter what.