Concussion grenade effect (QftIS)

This spell can't be cast except by throwing a concussion grenade (QftIS)

As an action, a character can throw a grenade at a point up to 60 feet away. With a grenade launcher, the character can propel the grenade up to 120 feet away.

This grenade explodes in a concussive blast that fills a 20-foot-radius sphere. Each creature in that area must make a DC 15 Dexterity saving throw, taking (6d6) force damage on a failed save or half as much damage on a successful one.