SRD:Sword of Life Stealing
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Sword of Life Stealing: This black iron +2 longsword bestows a negative level when it deals a critical hit. The sword wielder gains 1d6 temporary hit points each time a negative level is bestowed on another. These temporary hit points last for 24 hours. One day after being struck, subjects must make a DC 16 Fortitude save for each negative level or lose a character level.