The fiery cube is an explosive burst of flame that fills an area no larger than a 10-foot cube. It detonates with a low roar, creating a cube of fire. The fire inflicts 1d4 points of damage per level of experience of the spellcaster, to a maximum of 10d4. The fiery cube will fill any open space in its area of effect but does not expand beyond that area. Thus, if it were cast in a corridor 5 feet wide and 7 feet high, it would fill a volume 10 × 7 × 5.
The caster points his finger and speaks the range (distance and height) at which he wishes to place the spell's center. A streak of orange light flashes from the pointing finger, detonating in cubic shape at the prescribed place unless it strikes a solid object before reaching that place (early impact indicates an early detonation). Creatures in the area of effect that fail a saving throw vs. spell take full damage. Those who save successfully are assumed to have leaped part way out of the cube and take only half damage. (The Dungeon Master may rule that this is not possible.)
Besides causing damage, the spell ignites all combustibles in its area of effect and melts soft metals. Exposed items require a saving throw vs. magical fire to determine if they are affected. Items in the possession of a creature that makes its saving throw will be unaffected.
The material component of this spell is a tiny cube of bat guano, a small amount of sulphur, and a flake of phosphorus.