The Song of Boom

The Bard starts singing this song, “The sky is blue, the ground is blue too, now everything go BOOM!” 
   Everywhere the bard wants it, the ground explodes, and everything within 10 feet of the explosion must make a Strength saving throw, or else takes 5d10 combustion damage, or half as much on a successful one. 
   Everyone within 100 ft of the explosion must make a Constitution saving throw, or take 3d8 Thunder Damage.