Great shout

Great shout was an arcane evocation spell that produced a tremendous sonic force similar to a horn of blasting from the mouth of the caster.

Effects
There were at least two distinct versions of this spell. The original, presumably invented by a wizard named Daimos, was dangerous to the caster, requiring some of his or her own vitality in the casting, with possibly fatal results. It also required an item that radiated magic as a material component. A later version was much less taxing, did more damage, had a bigger area of effect, and only needed an arcane focus (which was not consumed in the casting).

Great shout had two areas of effect, one inside the other. The primary area of devastation was a narrow corridor emanating straight out from the caster. The secondary region of sonic punishment also emanated from the caster in the same direction as the primary but was in the shape of a widening cone that surrounded the primary on both sides. For the earliest version of the spell, the primary area was only one ft (30 cm) wide by eight ft (2.4 m) long,  while the later version had a five ft (1.5 m) square cross-section that extended out to the edge of the cone (a minimum of 65 ft or 20 m). The edge of the cone for the earliest version was 90 ft (27 m) away.

Daimos' great shout was not discriminating in what it affected. The primary area of sonic force could split boulders, flatten a log cabin, or breach a stoutly held gate. Objects in the path were likely to react as if they had been hit by a missile from a large catapult. Creatures took damage and were stunned for at least one minute and rendered deaf for at least two minutes. Outside the primary area, creatures took less damage but were still stunned and deafened.

The later version of this spell was particularly devastating to crystal, metal, or stone objects in the primary path of thunderous vibration. Anyone carrying items made from these materials could try to dodge out of the path of destruction, but if they failed, the items were likely to break or shatter. In the secondary area of effect, creatures were severely damaged, deafened, and possibly stunned for a few seconds. Any fragile or crystalline objects in the secondary area were also subject to breaking or shattering. Creatures carrying them could shield these brittle objects from damage by a successful dodge.

A silence spell was proof against great shout.

Components
Only verbal and material components were required to cast the earliest version of great shout. It needed an item that radiated magic, even if it was just Nystul's magic aura, and the item was consumed upon casting. The later version had verbal and somatic components but used an arcane focus of a small horn made from metal or ivory.

History
The first known instance of this spell was discovered by Ulthorn of Waterdeep when he acquired the Spellbook of Daimos around the mid–11th century DR. After his death the book disappeared, but great shout was subsequently used in Ankhapur on the Lake of Steam and in the outpost Twostars somewhere on the Golden Way. It was eventually published in Volo's Guide to All Things Magical shortly after the Time of Troubles and became generally known, but it was uncommon to find it.