Blackfire

A ray of necromantic energy springs from your hand, and on a successful ranged attack, a living target is engulfed in chill black flames that feed on the fuel of their targets life force. A creature engulfed in blackfire must make a successful CON save each round that the spell in in effect or take 1d4 points of Constitution damage and become nauseated. A creature that makes its save takes no damage and is sickened instead. In addition to its affects on the target, blackfire can spread rapidly, and any living creature adjacent to a creature engulfed in blackfire must make a DEX save or become ingulfed itself. 

Any creature whose Constitution is reduced to 0 or lower by the spell is reduced to a pile of ash, and can be returned to life only by a true resurrection or wish, the caster of which must succeed on a DC 30 caster level check to restore the target to life. If a creature succeeds on its CON save 3 consecutive rounds, the blackfire affecting it gutters out. The flames cannot be otherwise be extinguished by normal means (such as immersion in water or smothering), but an antimagic field, a successful dispel magic, or a remove curse spell snuffs it out. As well, a creature protected by death ward has immunity to blackfire's effects.