Maybe for "In Ravenloft" only, but I'm wary of making too many changes, since this is really covered by the usual blood drain and slam that we have already (right?). I'm not a big fan of too much in the way of exception-based mechanics.
Yeah, I'm just trying to work out how comfortable I am with putting it in. I guess it's ok in that limited sense. I just don't really want to fiddle much with the old conversion.
I had thought the weaknesses were for the general conversion, actually.
What about a caster level check required for curing the ability drain? That's consistent with some other difficult SAs (like mummy rot).
Leaving the current conversion as-is works for me.
I'd say make it Cha-based.
As precedent, I give you mummy rot
That seems like the closest to what we have here. Plus, it should be hard to cure.