I created this item because Void Staff and Last Whisper have little to no counter play.
35 MAGIC RESIST
UNIQUE PASSIVE: Impenetrable
The bearer takes 10% less damage from all sources (except true damage) before resistances. If the damage source has an item or passive effect that would penetrate armour or magic resist, this effect is doubled for that damage instance.
Say what you want about tanks being OP, you don't know how to counter them if you have such thoughts.