Can Void staff do percent magic reduction instead of percentage magic penetration?

The problem with void staff is that when you build or with it , it loses a lot of efficiency. Thats because magic reduction is calculated first, then magic penetration after.

So for example. If someone had 80 mr, would reduce that to 65mr, and void staff is then applied. That mean 35 percent of 65mr equals 23mr. effectively giving the target 42mr.

Now if void staff were to do percentage magic reduction, it would be calculated first. Hence 35 percent of 80mr equals 28. That means would then calculate off of 80-28 = 52 then minus 25 would equal a total of 27 mr.

See the difference. We went from 42mr to 27mr

The reason I suggest this is because Cassiopea can no longer by boots and is then forced to buy both void staff and together which as you can see is not so good.

If void staff were to change to percent magic reduction, everyone would be happy.