Hardening(Dragonlance Campaign Setting, p. 108)
Level: Sorcerer 6, Wizard 6, Forge (DCS) 7,
Components: V, S, M,
Casting Time: 1 standard action
Target: One item of a volume no greater that 10 cu. ft./level (see text)
Saving Throw: None
Spell Resistance: Yes (object)
This spell increases the hardness of materials (see Table 8-12: Substances Hardness and Hit Points in the Player's Handbook). Paper becomes harder to tear, glass becomes harder to break, wood becomes more resilient, and so on. For every two caster levels, increase by 1 the hardness of the material targeted by the spell. This hardness increase improves only the material's resistance to damage. Nothing else is modified by the improvement. For example, a longsword (base hardness 10) affected by a hardening spell cast by a 12th-level caster would have a new hardness of 16 for purpose of ignoring damage caused by someone using the sunder action. The sword's hit points, attack and damage modifiers, and other characteristics are not affected. The hardening spell does not in any way affect resistance to other forms of transformation. Ice still melts, paper and wood still burn, rock still becomes transmutable to mud with the proper spell, and so on.
This spell affects up to 10 cubic feet per level of the spellcaster. If cast upon a metal or mineral, the volume is reduced to 1 cubic foot per level.
Material Component: A pinch of diamond dust worth at least 100 gp per cubic foot of the item to be hardened.