My Wizard player keeps asking me which spells undead are immune to, and I keep getting mixed up with AD&D 3.5.
Can Blindness/Deafness be cast usefully on an undead dragon, for instance? The dragon in question is purely skeletal already, so she doesn't even have eyes or ears.
From Universal Monster Rules...
Undead have "immunity to any effect that requires a Fortitude save (unless the effect also works on objects or is harmless)."
The spell blindness/deafness has no effect if you cast it on a table, so undead are immune to the effect.