As 5 different casters within a 15 ft circle start singing and/or playing the Forbidden Requiem, they conjure a pulsating sphere of dark magic above them.

Other intelligent beings capable of singing, making rhythmic noise or proficient in an instrument within 30 ft of them or each other may join in to extend the range of the spell by 30 ft. each. 
Each time a caster or helper is disrupted, the spell loses 30 ft. of range and regains it next turn if the disrupted creature passes a DC 10 Charisma check.

As the Hymn ends, the dark sphere launches itself towards a destination chosen by the 5 original casters. Everything within a 15 ft. radius around the sphere's target, and every caster and contributor shrivel up and turn to dust, taking 1d4 Necrotic damage times their maximum hit points.