Talk:Teemo/@comment-24246352-20131224081519/@comment-4022742-20131226114918

Exactly what C4bal said. Even when reduces 35% of there MR before your flat penetration, if they have under 80 MR in the first place, you won't really have much benefit from it. Since flat penetration can't decrease below 0 MR anyways, only Resistance Shred can, think with.

So when they have 80 MR you'd apply void staff penetration, leaving 52 MR -6% (Devastating Strikes) -15 (sorcs) -15 (Liandry's) -7 (pen marks) works out at 11.8 MR. So you basically bought 26 magic pen with a void staff, and counteracted a bit of your Devastating Strikes. (calculation without Void staff would leave the pen at 38 MR a difference of 26)

If you are fighting people that are not buying MR, don't get a Void staff ;)