Arcane Cannon

You extend a finger toward a point within range that you don't have to be able to see. A beam of blinding energy flies in a straight line toward the target, penetrating almost all obstacles in its path. It bores a hole in anything it passes through with a diameter of about half a foot, but is stopped by more than 50 feet of wood or dirt, 10 feet of stone, 5 feet of common metal, a thin sheet of lead, or a creature. A creature in the beam's path must make a Dexterity saving throw. On a failure, it takes 6d10 force damage, or 4d10 if the beam had to pass through material to get to the target, or half on a success.