Just curious here.
I've been looking at options for combining SW, SWU and the expansions, and obviously checked out the DoW guidance for doing so. One of the things they suggest is switching out useless or contradictory race/power combos.
(Personally, I think I'd rather split the problem combos between the two base games, so that we don't have to worry about them coming up at all, but that's beside the point.)
Anyway, the section in the FAQ about this reads as follow:
Redundant or contradictory combos
If useless combos appear, you may replace their Special Power with another one, drawn at random from the Special Powers stack.
Known useless combos: Frightened Pixies, Immortal Elves, Seafaring Krakens, Tomb Ghouls, Tomb White Ladies, Underworld Spiderines, Vampire Kobolds, Vanishing Ghouls, Vanishing Priestesses, Vanishing White Ladies.
Now, Vanishing White Ladies aren't contradictory. It's just that the Vanishing Power (your token disappear when you go into decline) makes the White Ladies power (your in-decline tokens can't be conquered) useless.
By this same reasoning, wouldn't Vanishing Liches be a redundant combo? Their special ability makes their racial ability worthless. But Vanshing and Liches are from the same game.