The renowned fire wizard Daltim developed this spell some years ago to protect important items or structures against the various incendiary spells with which he was familiar. Proofing renders an inanimate object nearly impervious to fire, granting the affected item a +3 bonus to saving throws vs. magical fire (including a dragon’s breath), and a +6 bonus to saving throws vs. normal fire. This is cumulative with the saving throw bonus of a magical item, so a cloak of protection +4 could have a bonus of +7 to +10 on any item saving throws versus combustion effects. Remember that an item fails its saving throw on a natural roll of 1, regardless of any bonuses.
The item affected must be one discrete construction or object, although it can be articulated or composed of several parts (for example, a suit of armor, a catapult, a house, or a carriage). At 9th level, the wizard can proof an article of clothing or a small piece of furniture; at 12th level, a small vehicle or large piece of furniture; at 15th level, a small building or large vehicle; at 18th level, a medium building or a very large vehicle; and at 20th level or higher, a large building or small fortification. A character dressed in a completely proofed article of clothing (a large cloak) gains a +2 bonus to saving throws vs. fire.
The material component for proofing versus combustion is a fire-brick made with the ashes left from a phoenix’s fire. Seafaring wizards often use this spell to protect their vessels from hostile fireballs and various fire-throwing devices.