You magically transform the ground in a 20-foot-radius, 5-foot high cylinder into a pit of bubbling acid. Creatures in the area must succeed on a Dexterity saving throw or fall into the acid. Creatures with a flying speed have advantage on this save. If a creature succeeds on the saving throw, they safely land on the space closest to their original position that is not in the acid, or an adjacent space outside the acid if the closest one is already occupied.   When a creature enters the affected area for the first time on a turn or starts its turn there, the creature takes 4d12 acid damage.   As a bonus action while this spell is active, you can launch a large bubble of acid from the pit at a point you can see within 60 feet of the pit. The bubble explodes when it reaches the point, which can be in the air, and each creature within a 20-foot radius sphere of the bubble when it explodes must make a Dexterity saving throw. A creature takes 5d8 acid damage on a failed save or half as much on a successful one.   A creature that is not immune to acid damage must spend 4 feet of movement for every 1 foot moved within the acid.