Acidic Torrent

 You unleash a torrent of corrosive acid in a 90-foot cone. Each creature in that area must make a Dexterity saving throw. On a failed save, a creature takes 8d8 acid damage and is coated in acid for 1 minute taking damage at the start of each creatures turn. On a successful save, the creature takes half as much damage and is not coated in acid.

Creatures coated in acid a suffer the corroded condition.

Corroded : The creature takes 1d8 acid damage at the start of each of its turns. The creature’s AC is reduced by 2, and its armor or natural armor is visibly damaged. The creature's weapon attacks deal half damage, as the corrosive effect weakens its weapons. This condition last till you use an action to remove it; until the creature is cleaned by magical means or makes a successful Dexterity saving throw the end of it's turn. 

 At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d8 for each slot level above 5th.