Magic pen...
Triggers my OCD because armor pen is now called Lethality so you have almost every stat with it's counterpart:
AP - AD AS - CDR Health - Mana Armor - Magic resist (close to trigger...) Lethality - Magic penetration.......................................
So I propose that we name Magic pen: Hex
while the name might seem connected to Hextech, it's the only thing that comes to my mind when thinking about anti magic resistance... Now magic resistance could be called something else as well like... Veil? I dunno thoughts?