I have killed all thes mobs listed in this post and none of them give ding have looked all over the zone, not sure where they are at. About to delete and step back a quest.
Well, I'm not high enough level to get this quest yet (only had grabbed the generic info from beta), but I went hopping around looking for tainted erudites. I found five different types that had the void twitch to them, and listed them all in the quest write-up.
If someone can confirm which of these mobs update the quest, it would be appreciated! (I'm leaning toward the last three since they're level 90)