Cure Light Wounds (Token Cost: Free)

Cure Light Wounds
(Player's Handbook v.3.5, p. 215)

Conjuration (Healing)
Components: V, S,
Casting Time: 1 standard action
Range: Touch
Target: Creature touched
Duration: Instantaneous
Saving Throw: Will half (harmless); see text
Spell Resistance: Yes (harmless); see text

When laying your hand upon a living creature, you channel positive energy that cures 1d8 points of damage +1 point per caster level (maximum +5).

Since undead are powered by negative energy, this spell deals damage to them instead of curing their wounds. An undead creature can apply spell resistance, and can attempt a Will save to take half damage.