Ballant's Stonestrength

This spell causes any single stone structure, no matter what its size, to increase in structural strength by 10% per level of the caster. For example, a 10th-level wizard casting this spell on a stone gatehouse doubles its strength (+100%). The stone becomes tougher and more resistant to chipping and cracking. Any damage done to the structure reduces the magical strengthening first, so that even if greatly battered, the structure may escape unharmed at the expiration of the spell.

Since this spell affects only stone, it will not affect defenses of earth or wood. If a defensive structure contains a significant amount of other material, the DM can either adjudicate the effect of attacks locally or treat the magical augmentation as a percentage: If a wall is 40% stone, then the spell is 40% effective.

The spell completely repairs any stone-based creature, such as a stone golem, xorn, galeb duhr, and so on, but only for the duration of the spell. Damage taken within this time is taken from the magically repaired points first. When east upon a petrified individual, the spell provides virtual immunity to incidental chipping or breakage. The spell affects stone-creating magic, such as the wall of stone spell.

The material components are a small granite wedge and it pinch of powdered iron, which is sprinkled over the wedge during the easting.

Notes: Uncommon or rare for Earth mages; otherwise rare or very rare. (Updated from Dragon Magazine.)