Thunder roar

You channel a large amount of thunderous energy that you then release in a roar. All creatures  in a 35ft cube originating from you must make a constitution saving throw taking 8d6 thunder damage on a fail, half damage on a success. 

At higher levels: If you cast this spell using a spell slot of 4th level or higher, the thunder damage increases by 1d6 for each slot level above 3rd.