There seems to be some confusion here.
The 4th edition Nagash was not like a mummified Slann - that 4th edition Nagash was a monster with Greater Deamon like stats that could stand up to a Bloodthirster in combat (does actually make sense, in life he was a very skilled fighter as well as caster, so when he mutated into a 16ft giant the stats would make sense).
Perhaps we should put this particular discussion on hold for now and come back to him after we review the rest of the list, give us all time to think more on it?
The 4th edition Nagash was not like a mummified Slann - that 4th edition Nagash was a monster with Greater Deamon like stats that could stand up to a Bloodthirster in combat (does actually make sense, in life he was a very skilled fighter as well as caster, so when he mutated into a 16ft giant the stats would make sense).
Perhaps we should put this particular discussion on hold for now and come back to him after we review the rest of the list, give us all time to think more on it?