lead his improbable allies to capture Slaanesh...
This has me REALLY excited. It seems that perhaps, this might be the new "good/evil" Aelf rift: good Aelfs ally with the forest spirit types, and evil Aelfs forming some kind of pleasure cult. Remember, Morathi was devoured by Slaanesh in the end times - provided there is some kind of capture, could she be coming back?
It does make sense to have a bad-ass female sorceress as the leader of an "elf like" faction.