Acid touched

You smear an enemy with acid. Make a melee spell attack against the target. On a hit, the target takes 1d8 acid damage and its AC it reduced by 1 as the acid weakens the targets armour until the start of your next turn.

The spell's damage increases by 1d8 when you reach 5th level (2d8), 11th level (3d8), and 17th level (4d8).