Damage is initially still as before, but we added REF saves and a scaling down of the damage:
DC’s for the REF save are based on the power level of the acid, and the INT bonus of the creator of the acid. Weapon focus acts similarly to “spell focus” and adds to the DC of the save.
Damage on the acid is as follows:
Acid automatically degrades a die class after the second round. A successful save downgrades it a die class, until it downgrades from a d4 to nothing.