Thunder crash

A bolt of lightning flashes from your finger and strikes a space you can see within 150 feet and a 30-foot radius, all creatures within the area of effect must make a Dexterity saving throw of at least a 16 or take 5d12 lightning damage, taking half as much on a successful one, targets are also knocked prone and all flammable objects are ignited, creatures 10 feet away from the beam on their next turn must make a Constitution saving throw of at least 12 or take 2d12 damage or half as much on a successful one.