Erode

You blast a target with a glob of acid. The target must make a Dexterity saving throw. On failure, the target takes 8d4 acid damage immediately and becomes covered in acid. On a success, the target takes half as much damage and is not covered in acid. While covered in acid, the target takes 2d4 acid damage at the end of each of its turns. The target or a creature within 5 feet of it can end this damage by using its action to clear away the acid.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage (both initial and later) increases by 1d4 for each slot level above 3rd.

Source: Kibble's Generic Elemental Spells