The usual. The expedition has all been slaughtered, either by the cwyld, a big green dragon or the Undercity there. No-one's coming back, or you're all Shades, or that you're the CAUSE of the current problem because it's never happened before and so on.

[It's happened before, they all knew it, but people have short memories.]

Nay, think of it not as leaving them behind to a dark and unwelcome death but as bringing them back, to renewed life. The Coven may surely return them to their mortality, even if they are within a hair's breadth of becoming Shades.