Acid bubble

you create a 40 foot radius sphere of acid centered at a point within range. the acid sphere holds its shape until you lose concentration or the duration ends.Each creature in the sphere when it appears makes a constitution saving throw, taking 10d10 acid damage on a failed save or half as much damage on a successful one.A creature also makes this save when it starts its turn in the sphere or when it enters the sphere for the first time on its turn.A creature makes this save only once per turn.

when you break concentration or the duration ends, the acid bubble breaks its shape and flows outwards as a 10 foot tall wall of acid at 100 feet per round for 3 rounds.The interior area of the wall is also filled  with acid and counts as the wall of acid.Any creature that starts its turn in the wall or when it enters the wall for the first time on its turn makes a dexterity saving throw, taking 6d8 acid damage and 6d8 bludgeoning on a failed save or half as much damage on a successful save. A creature makes this save only once per turn.

Using a higher level spell slot: when cast with a 9th level spell slot, the bubble's damage increases to 11d10 and both  the wall's acid and bludgeoning damage increase to 7d8.