Grave Strike

Golden motes of light dance before your eyes. They converge on undead you look at, hovering about them and forming wedges of positive energy.

(Spell Compendium, p. 107)

Originally posted on D&D tools

Divination [Good]
Level: Cleric 1, Paladin 1,
Components: V, DF,
Casting Time: 1 swift action
Range: Personal
Target: You
Duration: 1 round

For 1 round, you can deliver sneak attacks against undead as if they were not immune to extra damage from sneak attacks. To attack an undead creature in this manner, you must still meet the other requirements for making a sneak attack.

This spell applies only to sneak attack damage. It gives you no ability to affect undead with critical hits, nor does it confer any special ability to overcome the damage reduction or other defenses of undead creatures.