Creamsteak, I'm still planning on playing the False Lover, although I just need to revise her stats a bit. I already have a background and motivation prepared but still thinking about putting it in story form. But basically, according to Creature Collection I the Unhallowed are very much afraid of the afterlife since they would suffer horrible punishment, more so than the curse they suffer in their unlives. Kathryn would see the divine spark as a way to circumvent all of that.
Perhaps Janos, because that sort of relation doesn't count for the purposes of Eldritch Legacy.
As I have stated previously, a much more broken use of it, free of problems would be to use it with a Master of the Secret Sound, since they can use any 9th level spell once per day as a spell like ability as a full round action, with that, you can accomplish anything whether it be Ice Assassin (new WotC spell, wayyy broken), Eldritch Legacy, etc...
I have been contemplating several ways to counter Mord's Disjunction before as well, I did come up with a few tricks, but most of them require around a level 18ish character to work with.
Btw, I normally, strictly play only spellcasters, and infinite spell DCs are quite easy to accomplish, but they're pretty bland. Btw, if anyone really wants a save, the Mysticism domain is the way to go, I don't plan on taking it, but if I did I'd have an extra +17 to all my saves.