[Wrana]

Yes, it solves (part of )disease problem. I also used it once on mages who were casting distant damage spells on provinces with quite possible (Fire) Domes. It worked, too - enemy blasted, damage coming back and burning my mage - and he just raises again as a Wight, with higher stats and no upkeep as an added benefit.
As for Twiceborn solution - I would prefer to copy spell stats in this case to save Twiceborn as is, adding Lich as another variant. Am not sure whether this would work, however.
As for cocktail - does somebody know whether any news from code divers had appear lately. I have one old version, but maybe something new exists?