Arcane Acid

Your hands glow a stunning lime green, and you summon a green orb of energy. You can then throw the orb onto the ground, which explodes into a pool of acid with a splattering range of a 15 feet square. A creature must make a constitution saving throw if they are splattered by the explosion. On a failed save, the creature takes 3d6 acid damage. On a successful save, the creature takes half damage. Regardless of success or failure, when a creature walks into the pool of acid, they take 1d8 acid damage. The acid pool stays there until the end of your next turn. 

When you cast this spell with a 4th level spell slot or higher, the initial damage increases to 4d6. Additionally, walking into the pool of acid will deal 2d8 damage.