Shatterhull

The shatterhull spell weakens a wooden structure that's immersed in water. Usually, it is cast upon a ship's hull. The spell weakens the hull within the area of effect, creating multiple leaks that can cause the entire area to give way. A seaworthiness check determines whether the ship is holed. If the check fails, the ship starts to sink immediately. Even if the check succeeds, the small leaks must be plugged or sealed; otherwise, a seaworthiness check must be made each subsequent hour.

The target need not be a ship, however. For example, shatterhull can be aimed at a wooden door in a flooded dungeon. In that case, the spell forces an immediate saving throw vs. crushing blow or the target is destroyed.

The material component of this spell is a thin glass needle, which is placed against the targeted surface.