Aspect of Acid

A caustic vapor swirls around you. For the duration, you gain resistance to acid damage. Additionally, whenever a creature within 5 feet of you hits you with a melee attack, they suffer 3d4 acid damage. 

As an action, you can channel the vapor into a mote of liquid acid and launch it at a creature within 30 feet. Make a ranged spell attack. On a hit, the target suffers 7d4 acid damage. Hit or miss, the spell then ends.

At Higher Levels: When you cast this spell using a spell slot of 4th level or higher, the damage dealt when you are hit increases by 1d4 for every two slot levels above 3rd, and the damage for the ranged attack increases by 1d4 for every slot above 3rd.