One of Us (Ex)
At 20th level, your form begins to rot (the appearance of this decay is up to you) and undead see you as one of them. You gain immunity to cold, nonlethal damage, paralysis, and sleep. You also gain DR 5/—. Unintelligent undead do not notice you unless you attack them. You receive a +4 morale bonus on saving throws made against spells and spell-like abilities cast by undead.