Elemental Erosion

Select one creature you can see within range, and pick one of these damage types: acid, cold, fire, lightning, or thunder. The target must pass a Constitution saving throw or feel the burn for one minute. The first time every turn the unfortunate target takes the damage you picked, it suffers an extra 2d6 damage of that type. The target looses resistance to that type, if it had any.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, you can select one additional creature for each slot level above 4th. The targets must be within 30 feet of each other when you target them.