Necromancy [Cold]
Level: Sorcerer 6, Wizard 6
Components: V, S, Coldfire
Casting Time: 1 standard action
Range: 60 ft.
Area: Cone-shaped burst
Duration: 1 round/level
Saving Throw: Will negates
Spell Resistance: Yes
Waves of frigid energy render all creatures with the fire subtype in the spell’s area shaken for the duration of the spell. Any creature with the cold subtype caught in the area of this spell loses its immunity to cold for the duration of the spell. Whether or not a creature makes its saving throw, it becomes immune to further castings of this spell for 24 hours.
Coldfire Component: Two ounces of coldfire (100 gp).
Source: Frostburn, page 106.