This cooperative spell requires at least three priests casting the spell simultaneously.
At the time of casting, the priests must be within 10 feet of each other. Upon completion of the spell, the priests sing a single, dissonant chord. The result of the spell depends on the number of voices in the choir.
Trio. In this form, the spell projects a cone of sonic force 120 feet long and 40 feet wide at the base. All creatures within the area of effect must save vs. spells or suffer 2d4 points of damage. Those who successfully save suffer only 1d4 points. Undead suffer a -2 penalty to their saving throws.
Quartet. With four voices, the spell has the same area of effect as described above.
However, all those who fail their saving throw suffer 2d4 points of damage and are deafened for one round. Those who successfully save suffer half damage and are not deafened. Undead creatures are not allowed a saving throw.
Quintet. Five singers produce a chord of major power. All within the area of effect suffer 3d4 points of damage (saving throw for half damage). Undead are not allowed a saving throw. All creatures are deafened for one round. Furthermore, pottery, glassware, crystal, and similar breakable goods must save vs. fall or be shattered.
Ensemble. An ensemble of singers consists of six to ten priests. In this case, the area of effect increases to a cone 180 feet long and 60 feet wide at the base. All creatures within this area suffer 1d4 points of damage per priest and are deafened for 1d4 rounds.
A successful saving throw vs. spell reduces the damage and duration of deafness by half.
Undead creatures of 3 hit dice or less are immediately destroyed. All other undead suffer normal damage, but are not allowed a saving throw. Glass, pottery, crystal, bone, and all wooden items that are the strength of a door or less (chests, tables, chairs, etc.) must save vs. crushing blow or be shattered.
Choir. The most powerful group, a choir, requires eleven or more priests. In this case, the area of effect expands to a cone 300 feet long and 100 feet wide at the base. All within the area of effect suffer 1d6 points of damage per priest to a maximum of 20d6. A saving throw vs. spells reduces the damage to half. Those who fail to save are deafened for 1d10 rounds; those who succeed are deafened only 1d6 rounds. Undead creatures of 5 hit dice or less are immediately destroyed. Undead with more hit dice are not allowed a saving throw. Structures within the area of effect are damaged as if they suffered a direct hit from a catapult (one hit per four priests in the choir). Doors, chests, and other breakable items are instantly shattered.