Internal Fire

(Oriental Adventures, page 106, DnD 3.0)

Evocation[Fire]

Level: ; Wu Jen 9; , Flame 9
Components: V, S
Casting Time: 1 round
Range: Medium (100 ft. + 10 ft./level)
Target: Creatures with total HD not exceeding your level, no two of which may be more than 20 ft. apart
Duration: Instantaneous
Saving Throw: Fortitude partial
Spell Resistance: Yes

This spell creates a deadly raging heat in the internal organs of the targets, causing them to burst into flame from the inside.
Death occurs instantly.
A successful Fortitude save instead deals 6d6 points of damage, +1 point per caster level.
Focus: An iron brazier filled with red-hot charcoal.