Acidic Prison

You conjure up a sphere of acid with a 5-foot radius at a point you can see within range. 

Any creature of size Large or smaller in the sphere’s space must make a Strength saving throw against your spell DC. On a successful save, a creature is ejected from that space to the nearest unoccupied space of the creature’s choice outside the sphere. A creature can choose to fail it. On a failed save, a creature is restrained by the sphere and is engulfed by the acid and takes 1d6 acid damage. At the start of each of it's turn it takes 1d6 acid damage as the acid starts to dissolve the creature. At the end of it's turn, a restrained creature can repeat the saving throw, ending the effect on itself on a success.

As an action, you can move the sphere up to 30 feet in a straight line. If it moves over a pit, a cliff, or other drop-off, it safely descends until it reaches solid ground. Any creature restrained by the sphere moves with it. You can ram the sphere into creatures, forcing them to make the saving throw. The sphere can hold one Large, two medium, one medium and two small or four small creatures. If you try to trap another creature in the sphere while its already full the largest creature gets ejected.

When the spell ends, any creature restrained by the sphere is knocked prone in the space where it vanishes.

At higher Levels: When you cast this spell using a spell slot of 5th level or higher, add 1d6 to the intital and the continuous acid damage for each level beyond the 4th. If you cast this spell as 6th level or higher the restrained creature also starts to suffocate.