Shipshock

This spell acts as a security device, protecting ships from underwater attacks. (It can protect other submerged wooden or reed structures, too.) Once cast, shipshock does nothing until the vessel is touched by a living underwater creature with Intelligence above “animal.” Most fish don't qualify, so don't accidentally discharge the spell.

When the spell is triggered, the ship releases a bright blast of electrical energy, inflicting 1d6 points of damage per level of the caster, to a maximum of 15d6.

The individual who touched the ship (and caused the blast) makes a saving throw vs. spell; success indicates that only half damage is incurred. In addition, all creatures in the water within 100 feet of the discharge must make a saving throw vs. spell. Success means they surfer no damage; failure means they surfer half.

The blast does not harm those who are out of the water, including any aboard the ship, nor does it harm the ship itself. Shipshock carries only one charge. If the blast is not triggered before the duration of the spell elapses, it fades away harmlessly.

The material component of this spell is a small silver rod, which is pushed into the protected ship's keel like a nail. The rod is consumed if the blast is triggered, but not if the charge merely fades.