I hate how just about any magic resist item basically means any ap damage is basically gone unless you void against anyone thats builds magic resist and that it costs 2650 gold if you ever want to do damage against any large mr items meanwhile an ad champ can just get last whisper for 1300 gold and get by fine against armor and upgrade later for when they need the passives for more tank killing or grievous wounds.
apparently ap champs shouldnt damage tanks because they have burst heh
correct me if im wrong...
dont mages rune 9 flat magic pen reds? dont mages either take piercing thoughts for +7% magic pen or precision for flat magic pen
and nearly all mages get 
for +15 magic pen
so with +8 magic pen from runes and +15 magic pen from boots thats +23 flat magic pen and either the +7 % or 14 flat magic pen @ lvl 18 from precision
so if you run precision and know teams arent likely to stack MR then having +37 flat magic pen is pretty good
or the +7% magic pen from piercing thoughts so the more mr they have the more magic resistance you ignore
