Corrosion bomb

spits a ball of extremely corrosive acid no more than 12 inches across towards a location of his choice up to 20 feet away, when it hits the targeted location it explodes covering 10 feet around the epicenter in acid that anything grounded standing in it have their movement halved and -1 ac while standing in the acid, and if anything dies in the acid any non-key items will be destroyed, and if they happen to be in the blast radius they have to take a dex saving throw which if they fail they will take 1d6, at rank 4 you can add a damage die or increase damage to d8, at rank 8 add 1 damage die or increase damage die by 2, at rank 12 you get both a damage die and and 2 more damage die, at rank 16 increase ac reduction or increase the blast radius to 20 feet, after you ascend at rank 20 you add 5 feet to the blast radius or add a damage die