Thunderstorm

You call down a booming thunderstorm around you. Each creature other than you in a 15ft radius must succeed on a constitution saving throw or take 8d6 thunder damage and be knocked back 35ft. On a successful save, it takes half as much damage and is knocked back 10ft.

If you cast this spell using a spell slot of 6th level or higher, increase the damage by 1d6 for each slot level above 5th.