A mass of slime and goo erupts from you in a 100 ft. cube in a direction of your choice. For the duration, that area counts as difficult terrain. Each creature in the cube when the spell is cast must make a Dexterity saving throw. On a failed save, the creature takes 10d6 acid damage and is knocked prone. On a successful save a creature takes half damage, and is not knocked prone. Each turn a creature spends in the area, it must make a Constitution saving throw, taking 5d6 acid damage on a failed save, and half as much on a successful save. Every time a creature moves 5 feet or more while in the area, it must make a Dexterity saving throw, or fall prone. When the spell ends, you gain temporary hit points equal to half the amount of damage you dealt to one creature of your choice.