Kingdoms in Death
Your special melee or ranged attack with one type of weapon is especially effective against undead.
Prerequisite: Proficiency with selected weapon, Weapon Focus with selected weapon, Weapon Specialization with selected weapon, fighter level 4th
Benefit: You gain a +4 bonus on all damage rolls you make using the selected weapon type against undead.
Special: A fighter may select Necropotent as one of his fighter bonus feats.
Rulebook: Libris Mortis (p. 29)
Edition: Supplementals (3.5)