Pardon the thread necromancy, but I have exactly the same question. And is death ward the relevant prerequisite? I'm trying to determine if death ward grants protection to ability damage/drain from the undead.
The shadow entry says that "The touch of a shadow deals 1d6 points of Strength damage to a living foe. A creature reduced to Strength 0 by a shadow dies. This is a negative energy effect. " However, other undead don't include the reference to negative energy.