Thunderdome

A 15-foot-radius immobile sphere of force springs into existence around you and remains stationary for the duration. The spell ends if you leave its area. Spells and other magical effects can’t extend through the sphere or be cast through it. The atmosphere inside the space is comfortable and dry, regardless of the weather outside.

Each creature within the 15-foot-radius sphere centered on the spellcaster must make a Constitution saving throw. A creature takes 4d6 thunder damage immediately and 2d6 thunder damage at the end of their next turn on a failed save. On a successful save, they only take half as much of the initial damage and no damage at the end of its next turn. A creature made of inorganic material such as stone, crystal, or metal has disadvantage on this saving throw.

All creatures within the 15-foot-radius sphere are trapped within and cannot exit the area of effect.

A nonmagical object that isn't being worn or carried also takes the damage if it's in the spell's area.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage (both initial and later) increases by 1d6 for each slot level above 4th.