Tidal wave

Tidal wave was an arcane alteration spell that created a huge destructive wave in a large body of water. In terms of damage and scope, it was one of the most powerful spells known in the Realms since Mystra's Ban in the Year of Sundered Webs, &minus;339 DR.

Effects
This spell took thirty minutes to cast and was so taxing on the caster that he or she could not channel magical energy again for a few days afterward.

When cast upon a large body of water, tidal wave created a single wave that was 75 ft (23 m) high and at least 1,800 ft (550 m) wide (even wider for higher level casters) that traveled in a chosen direction. The ponderous wave traveled at a pace slower than a walking gnome at 150 ft (46 m) per minute, and could not be diverted once a direction was set. The spell lasted for over three hours (again, even longer for more experienced casters) or until the wave hit a shoreline.

Swimming creatures near the surface of the water had a chance to move through the wave and come out the other side unscathed, but the unlucky were pummeled and crushed. Ships in the path of the wave were driven before it and required superior seamanship just to avoid being swamped. Only a feat of extraordinary seamanship could achieve a cresting of the wave, preventing any major damage.

When the wave reached the shore, the real devastation began. All ships being driven by the wave as well as everyone and everything within 50 yd (46 m) of the shore were struck by the powerful wave and catastrophically damaged. As the water surged inland, the destructive force gradually decreased until it was finally exhausted 500 yd (460 m) from the shore.

Components
In addition to verbal and somatic components, this spell required the caster to strike the surface of the water with a plank made of wood in the desired direction the tidal wave was to travel.

History
This spell was associated with the pirates that roamed the Sea of Fallen Stars.