Corroding Strike

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects and takes an additional 1d4 acid damage. At the start of the creature's next turn, it takes 1d4 acid damage again.

Both instances of this spell's damage increase by 1d4 when you reach 5th level (2d4), 11th level (3d4), and 17th level (4d4).