I find the Blood Witches with the Hag (usually a min unit for me) are well worth it. If my opponent over commits resources to deal with them, then great. If not, then you have a unit that can contest distant flags/zones and run amuck in the back ranks killing support. At the very least, it brings another source of Dark Shroud to the table. My min unit with Hag is invariably useful in some way and worth it’s points.