Recently, I noticed an important point that should be reflected in the "Immunity with Sphere" section: Blindness does not affect undead creatures, even with the Sphere of Vulnerability! I encountered this and was very upset because in battles with powerful necromancers, I had to change my tactics "on the fly" (I've already written somewhere here that Blindness is a very valuable spell if used wisely).
(Василь Симоненко. Люди – прекрасні)