If I got all right healing spells and buffs (like bless) the ones that help living damage undeads and vice versa. They mentioned that even eating food can damage them. Basically you should look on all spells for 180 degrees. Like poison cloud that damages living, heals undead and all like that. I am not sure that they mentioned any buffs that make them more powerful.
Only trait on undead I noticed was his racial skill "play dead" where basically he just drops dead and fakes that he is like dead and enemies leave them alone.
